I've been having a dispute with Ed Cho about pitch counts.
Cho thinks they're given too much importance. I disagree. I think that for young pitchers, it's very important to keep a low pitch count. Pitching puts extreme stress on a pitcher's arm. I read an article once about how guys who pitch a ton of innings early in their career burn out. (Note, I'm using innings as a proxy for pitch count here.)
To test this, I looked at career leaders in wins. (Because the general consensus is that pitching these days is tougher than the 50's because the 7-9 hitters are so much better, I arbitrarily required a pitcher to start his career in 1960 or later to be considered.) I look at how many innings these guys threw. Because they are the career leaders, they are the most durable arms in baseball over the last 40 years. I assign an age based on that pitcher's age at the start of the season. I only look up to the age 26. The first number is the age the pitcher first threw 100 innings, the second number is 200, the third is 300 (if he pitched 300 before turning 27)
Carlton 22 23
Ryan 21 25 26
Sutton 21 21
Clemens 22 24
P. Niekro (a knuckleballer, he's obviously not too relevant)
Perry 25 25
Seaver 23 23
Maddux 20 21
Blyleven 19 20
Jenkins 22 23
Palmer 20 20 23
Glavine 22 24
Marichal 23 24 25
R. Johnson 25 26
Tanana 20 20
Tiant 23 26
Hunter 18 20
Note: Catfish Hunter's last season was when he was 33.
My point is, it looks pretty clear to me that pitchers who last a long time didn't throw a ton of innings when they were in their early twenties. This specifically came up with Cho when we were talking about the Cubbies. Kerry Wood threw 166 innings when he was 20. He lost the next year to injury, and surpassed 200 innings when he was 24 (which is about right, I think). We'll see if he lasts. Mark Prior threw 116 innings at 21, 211 at 22. To me, that's worrisome. Why take a chance?
Mulder 154 when he was 23, 200 when he was 24. Zito threw 92 when he was 21, 200 when he was 22, and he has arm troubles. Hudson threw 136 when he was 23, 200 when he was 24.
I don't know, but it looks like a trend to me. If I were a GM, I'd limit innings until a pitcher turned 24.