Why can't modern starting pitchers consistently pitch on 2-3 days rest?

Question

I've been browsing through some historical pitching stats at Baseball-Reference.com.

It seems that in the 1910s and 1920s, starting pitchers frequently pitched on 3 days rest, sometimes pitched on 2 days rest, and occasionally even pitched on 1 day of rest. Back then, the league leaders always had over 40 games started per season (which was 154 games long).

It seems like pitching on 3 days rest was fairly common until the 1980s. Then in the 1990s pitching on 4 days rest became the norm, and nowadays the league leader in games started never has more than 35 (in a 162 game season).

Athletes should always get better in terms of strength and stamina due to improvements in training techniques and equipment, so why is it that starters nowadays can't pitch consistently on 3 days rest like they did several decades ago? Most teams' fifth starter isn't very good, so it would be better for them if they could just have a 4-man starting rotation.

I know in the playoffs nowadays, teams sometimes try to have their ace pitch on 3 days rest. If a pitcher doesn't pitch well on 3 days rest, then the poor performance is blamed on the fact that he only got 3 days rest. (See Clayton Kershaw in the 2014 playoffs as an example.)

And nowadays if a pitcher somehow pitches well on 2 days rest, like Madison Bumgarner did in Game 7 of the 2014 World Series, it is hailed as a legendary, impossible, once-in-a-lifetime performance. I'm not sure it would have been such a huge deal if it had happened 100 years ago.

Answer 1

The major reason players pitch on four days rest is that they are better pitchers when they do so. They are able to throw harder, throw more pitches, and throw more difficult pitches (with more spin/etc.) than they would if they had less rest. They are also less prone to injury.

Some evidence exists that pitching on three days rest in the postseason (where it's somewhat common); for example, this article at BleacherReport finds pitchers pitching on three days rest (who are usually the ace or #2 pitcher of a team) have a 4.48 ERA and win less than 40% of the games they pitch. Some of this may be pitchers being unused to pitching in those circumstances (and pitching against fairly good teams, it being the postseason); but it does seem logical that pitching on short rest is somewhat harder.

The other major factor is the fact that for most teams, the fifth starter isn't all that much worse than the fourth starter. While a few teams might have four great starters and then a poor fifth starters (the 2014 Tigers post-Price trade for example), the large amount of starting talent plus the ability to use multiple relievers means you wouldn't lose much by starting that fifth starter, particularly if it allows you to have better performances on the other four days.

If the question is what's the difference between then and now, you'll probably find that the major difference is in modern strength techniques allowing pitchers to throw that much harder; this both increases the number of pitchers who can competently pitch, and increases the benefit from rest - I'd rather have my starter hit 94 on most of his pitches every fifth day, rather than throw at 92 every fourth day.

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The other issue with this is the premise of the question - namely, that the four man rotation was very common 20-30 years ago. This is simply untrue.

Reading SABR's Origins of the Pitching Rotation by Frank Vaccaro, the 5 man rotation existed in the 1930s, and even in the 1930s was the most common kind of rotation. See the chart (unfortunately very low DPI) in that article; by 1935 more teams pitched with a five man rotation than a four man rotation. If I have some time (maybe on the train home) I'll download the retrosheet data he used and make a better chart.

In the 1970s, you typically had 20-30 pitchers who started at least 36 games (a true four man rotation would start 40). Given every pitcher on a team would start that many games in a true four man rotation, that means a whopping 8 to 10 teams may have had four man rotations; the rest likely had five man rotations. If you up the number of games started to 40 (again, the true four man rotation), you are in the teens or less in the 1970s - so maybe a handful of teams had a true four man rotation.

Many teams had modified 4 man - 4 day rest rotations during this period, where a team had four starters and used a fifth periodically when needed to keep them on four day rest. This often led to #1 pitchers having 36-37 starts, so 3 or 4 more starts than the true 5 man rotation (33). To some extent this fell out of style finally in the late 1980s and 1990s, where Bobby Cox and Joe Torre used true 5 man rotations with great success; while it seems like you might as well keep your aces on 5 days rest, it may be that an occasional sixth day is helpful for their rest, and/or keeping the 5th man on a regular rotation is better than having him only pitch every 10-20 days. (It also may be largely irrelevant, who knows.)

Either way, anyone arguing that "most teams had four man rotations in the 1970s" is misremembering, probably thanks to folks in the 1970s and 1980s misremembering themselves.

Answer 2

Coach-D's comment to the original question is a fair one - namely, that players are still physically capable of such feats but haven't been trained to do so. There are at least two other compelling reasons, however.

First, we live in an era of specialization when it comes to baseball. Relief pitchers capable of coming into a ballgame and throwing in the mid 90s is a common sight today, whereas it would have been a rarer thing several decades ago (with the big increase in usage of relievers occurring between the 60s and the 90s). When even a setup man is capable of pitching like an ace for one inning, the incentive to build up your rotation to the point where your starting pitchers are capable of tossing more innings isn't as strong.

Second, teams are far more concerned about injuries today than they were fifty years ago, and pitcher injuries in particular receive far more scrutiny than they used to. Many talented pitchers back then hurt their elbows or shoulders and ended up losing out on what would have otherwise been a potentially solid career. This was, effectively, a screening process whereby the players less likely to get hurt stuck around and racked up high innings totals.

Answer 3

I think the major reasons for the extra days of rest is career longevity and potential for injury. As many of the answers have said pitchers can condition their body and particularly their arm to throw on shorter rest. Current Major League relief pitchers are conditioned to throw on several concurrent days. However, they throw less pitches over a 5 day span than a starting pitcher. And as the original question pointed out starting pitchers can be successful on limited rest (Madison Bumgarner). But on average a starting pitcher would have a much shorter career if he pitch serval years with only 3 days rest between starts. Today Major League clubs are looking to preserve good pitcher into their late 30s, this would not be possible on 3 days rest between starts. More often that not pitching injuries are caused by fatigue. If pitchers threw more often on 3 days rest the chance of fatigue is more likely and therefore the chance for injury is more likely.

I tried to find some research that would support my argument like Major League pitcher career length. But pitching career length is very short on average. I am familiar with the mechanics of throwing a baseball and it is a big stress on the small muscles, ligaments and tendons in the arm. The less they are used the longer the will function.

Answer 4

Basically, back in the 1920's and 1930's pitchers didn't pitch with maximum effort all game like they do now. That is why you hear of stories where a pitcher would pitch both games of a doubleheader. Nowadays pitchers are throwing with maximum effort right from the start. They have to because hitters are that good.

It's not that they aren't in good enough shape to do it, it's mainly because the hitters are just so good now that they have to throw with maximum effort all the time, and if they don't hitters will jump all over them.

Answer 5

I am going to answer this with my coaching glasses on. Mainly a football coach but have been involved, especially at high school level, with baseball team's conditioning programs. Also was a decent pitcher in high school with a low 80s fastball.

I see three factors that have slowly increased rest needed for pitchers:

• added muscle. Anecdotally I grew up playing baseball and I had a cannon. As I got older (8-9) I started playing football. Still good. As I got a little older 14-15, started weight training - mainly legs/back but some arms/chest. By 17 had elbow issues constantly throwing a baseball but football was fine. I don't think weight training is the #1 issue but it contributes.

• pitchers throw harder now. The baseball world is whacko with radar guns. It is FREAKING CRAZY and DUMB. A high school kid who throws a gem shutout might have a bad outing to scouts because fastball topped off at 81 mph. So guess what? Kids know this, their coaches know this, their dads know this, their pitching coaches know this... So what happens? They tweak their motion and throw as hard as they can all the time. What do we get in the majors? Yes, pitchers that throw as hard as the can all the time. Very little emphasis on anything else until you hit the highest level. What would they get if the kid that threw that shutout always got the scholarship? More players that worried about spotting the ball, working hitters, throwing variety of speeds and pitches, and so on. The cream doesn't always rise, because sometimes we throw out the cream. (And I am saying this as a pitcher whose only trait was to throw hard) Greg Maddux was one of the most dominant pitchers of the last 50 years and his fastball would be outdone by most college pitchers. He also didn't have a fluke pitch (knuckleball). Greg said that he could pitch every 3-4 days if needed - I don't think he pushed this since he loved golf (and one hell of a golfer). Why aren't there more Maddux's? Because those kids aren't getting college scholarships, scouts are not signing them and there is basically nothing you can do on your own. A 22 year-old could get out 15 minor leaguers in a row in some fall ball league and no one would care unless he threw close to 90 or struck them all out.

• training, training, training. It all starts at the youth level. Most kids only pick up a baseball at practices. They play video games for fun, not catch. The fact that kids aren't out playing catch 5-7 days a week probably has a lot of long-term effects on their arm strength, ability to recover, flexibility and so on. I personally pitched from 5 years-old on. I can't ever remember my arm being sore until I started lifting. We played catch every day, lots of long toss. I pitched at least 3 games a week. Basically I started every game and did the max innings (4 at the time) and would start the next game if league let you (leagues/tournaments only limited pitching limits so you couldn't ride one kid to a championship not because of injury risk). Could the training be changed? Yes. But it would probably take a few years of development under new routine to see results and often young players aren't anywhere or even in the same organization for a few years. A few major league teams have their own special sauce (Cardinals focus on a lot of long toss on off days) but they are fighting with "stars" who are making millions and already have their routine.

My quick analysis - Teams could easily have their pitchers go every 3 days. They would first need to limit their weight lifting that tightens or stresses the shoulder, chest, forearms, elbows. I am not saying stop it but low impact stuff. They would systemically train their players to almost throw every other day with even some throwing on off days. But most importantly they would have to give up the radar gun mentality.

Will this ever change. I can't see it now at the MLB level. Pitchers are getting paid. If they pitched 25% more they would want a raise. Teams won't give them a raise until it works, players (players' agents) will fear extra pitching equals more injuries - which historically is incorrect, and then the two sides will go around in circles. It would basically take one star to do this and win over his teammates, which may start another team trying the strategy.

Answer 6

Obviously 100 years ago, players were more ruggy and tough compared to modern day players. They were often farm workers or factory workers. Therefore, their bodies could endure more than our bodies due to their strength working in factories or farms every day. That way, pitching feels easy compared to what we feel when we are not working the farm every day from dawn to dusk. People in general had a much more tough part to them because most did not have jobs that were not dealed with hard intense labor every day, so they were able to pitch more with less rest than modern day humans and players.