Why Are Modern Pitchers So Fragile?

Another request.

Why are modern pitchers so fragile? They pitch fewer innings per game, start fewer games, and have more days rest between starts. In addition they have much better training and medicine to cope with the stresses of pitching.
I have heard it repeated that there will no longer be 300 game winning pitchers. What happened to the Nolan Ryans and the Bob Gibsons?

Unfortunately, I don’t have very good data to examine exactly how total pitches thrown have changed going too far back in time. But, given the pattern going back to the late-1980s, I think it’s safe to assume that the extreme loads of pitchers are declining, even though the average pitching load has remained constant at about 99 pitches per game.
Maximum pitches thrown per game

Using some simpler measure of workloads, innings pitched, the pattern is interesting. The figure below shows the change in total innings pitched in a season over time for the maximum number of innings pitched, and by 95th and 75th percentiles, and the median (minimum 10 games started).


Though there has been a general decline in pitcher workloads over time, there was a bump in the late-1960s and early-1970s, when pitching loads increased over what they where in the 1960s. Since 1962, when the leagues both started playing 162 games a season, there have been 65 pitcher-seasons with 300 or more innings pitched. The last one occurred in 1980 when Steve Carlton threw 304 innings. Below are a table of the number of 300-inning performances by seasons and a list of those performances by pitchers.

Year	Count
1962	1
1963	3
1964	1
1965	2
1966	4
1967	1
1968	4
1969	9
1970	4
1971	4
1972	4
1973	7
1974	8
1975	4
1976	2
1977	4
1978	1
1979	1
1980	1
Total	65
Pitcher		Year	IP
Vida Blue	1971	312
Bert Blyleven	1973	325
Jim Bunning	1967	302.33
Jim Bunning	1966	314
Steve Carlton	1980	304
Steve Carlton	1972	346.33
Jim Colborn	1973	314.33
Larry Dierker	1969	305.33
Don Drysdale	1965	308.33
Don Drysdale	1962	314.33
Don Drysdale	1963	315.33
Don Drysdale	1964	321.33
Bob Gibson	1968	304.67
Bob Gibson	1969	314
Dave Goltz	1977	303
Bill Hands	1969	300
Catfish Hunter	1974	318.33
Catfish Hunter	1975	328
Fergie Jenkins	1968	308
Fergie Jenkins	1969	311.33
Fergie Jenkins	1970	313
Fergie Jenkins	1971	325
Fergie Jenkins	1974	328.33
Randy Jones	1976	315.33
Jim Kaat	1975	303.67
Jim Kaat	1966	304.67
Sandy Koufax	1963	311
Sandy Koufax	1966	323
Sandy Koufax	1965	335.67
Mickey Lolich	1974	308
Mickey Lolich	1973	308.67
Mickey Lolich	1972	327.33
Mickey Lolich	1971	376
Juan Marichal	1966	307.33
Juan Marichal	1963	321.33
Juan Marichal	1968	326
Sam McDowell	1970	305
Denny McLain	1969	325
Denny McLain	1968	336
Andy Messersmith1975	321.67
Phil Niekro	1974	302.33
Phil Niekro	1977	330.33
Phil Niekro	1978	334.33
Phil Niekro	1979	342
Claude Osteen	1969	321
Jim Palmer	1970	305
Jim Palmer	1976	315
Jim Palmer	1977	319
Jim Palmer	1975	323
Gaylord Perry	1974	322.33
Gaylord Perry	1969	325.33
Gaylord Perry	1970	328.67
Gaylord Perry	1972	342.67
Gaylord Perry	1973	344
Steve Rogers	1977	301.67
Nolan Ryan	1973	326
Nolan Ryan	1974	332.67
Bill Singer	1969	315.67
Bill Singer	1973	315.67
Mel Stottlemyre	303	1969
Luis Tiant	311.33	1974
Wilbur Wood	320.33	1974
Wilbur Wood	334	1971
Wilbur Wood	359.33	1973
Wilbur Wood	376.67	1972

Thus, it seems that teams tried to ramp up pitcher workloads just prior to the modern decline. What happened in the 1960s and 1970s that caused an increase in pitcher workloads? Did teams realize the ramp-up was a mistake, which caused the trend to reverse? This was an era of low offense, and the mound was lowered and the designated hitter added as a response. Was there a shift in pitching philosophy or did something structural cause this shift? I’m open to suggestions. The bump may offer a clue.

Aside from the bump, what has caused the declining trend in workloads? Most obviously, the rise of the five-man rotation gave pitchers fewer games to cover. On top of this, teams began to rely more on relievers within games pitched than in the past, going with fresh pitchers in late innings rather than asking starters to pace themselves. The number of complete games has declined continuously since the late-1970s.

I think the decline in pitching loads is less a response to a toughness of pitchers than it is a change in pitching philosophy. Every year, someone is supposedly going to go to have four-man rotation, but then we never hear any more about it. Whether that is because no manager has the guts to stick to a plan that is easy to criticize when injuries that were bound to happen anyway happen, or because the five-man rotation actually leads to better pitching, I don’t know. I have found that days of rest appear to have little impact on performance, so I don’t believe there is any performance benefit from giving pitchers more rest days in a five-man rotation. I’d love to see a team go with a four-man rotation from start to finish.

As for the increased use of relievers, I believe managers have discovered that 100% mediocre arms can be more effective than paced good arms. Teams can increase their chances of winning by going to the bullpen, exploiting match-ups, and pinch-hitting for pitchers. Furthermore, I’ve found some evidence that fewer pitches per game can improve future performance among starters.

In summary, my best guess is that the decline in pitching loads is part fad (four-man rotations) and part innovation (relievers can be better than paced starters).

UPDATE: In my initial cut and paste of the 300-inning pitchers I accidentally left off six seasons at the bottom of the table. I have added the missing seasons.

5 Responses “Why Are Modern Pitchers So Fragile?”

  1. Rich says:

    What about the toll pitching takes on arms leading up to the major leagues? I think it’d be safe to say that with all of the young traveling all-star teams that the best players (pitchers) play on, there’s a possibility that some are being over-utilized. It would be interesting to see if there is a connection or correlation between the rise of all of these leagues and teams and a decline in the innings of a major league pitcher.

  2. Randy Hill says:

    I think your conclusion is probably right on, that managers realized that fresh mediocrity is more effective than exhausted skill. But you make the mistake of trating one ‘inning” is the same as any other “inning”, despite large changes in offensive environments from era to era. This year in the NL the average runs scored per game is 4.35, and average OBP is .324. In 1968 it was 3.0 and .300. Might pitchers have thrown a bit fewer pitches to get through each inning during the 1960s?

  3. JC says:

    I’m trying to answer why pitchers are pitching less than they used to. I used pitch count data as far back as it goes, which shows pitchers are throwing fewer pitches. I also looked at batters faced, but the trends were almost identical to innings pitched, so I went with the more frequently used measure of pitching load. One of my suggested answers is that pitchers are being asked to pace themselves less.


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  2. [...] Why Are Modern Pitchers So Fragile? (Sabernomics). J.C. Bradbury notes, among other things, that “…managers have discovered that 100% mediocre arms can be more effective than paced good arms.” [h/t BBTF] [...]