Pitchers & Volatility Levels

In the past two weeks, Brad Penny and John Smoltz, both very experienced veteran pitchers, were released by the Boston Red Sox. Signed during last season’s offseason on incentive based contracts, the Red Sox nation bought low for pitchers with lots of question marks.

Smoltz’s season with the Red Sox can be described as disastrous. Here was his line with the New England-ers:

2 Wins, 5 Losses, 40.0 Innings Pitched, 59 Hits Allowed, 37 Runs Allowed, 8 Home Runs Allowed, 33 Strikeouts, 9 Walks Given, 8.32 ERA, 1.70 WHIP, .343 BAA

Yeah, over 40 innings, Smoltz looked like an aged man who could not locate his pitches where he wanted them. His velocity was there, but location was the key flaw that many saw in his pitching for the Red Sox. But the key question is, has Smoltz digressed to become a bad pitcher? A good article to look over (if you have time) compares Smoltz’s past 40 innings to Jered Weaver’s (a 26 year old pitcher who, many believe, has a bright career ahead of him) past 40 innings. The article bases its argument on the fact that a sample size of 40 innings is very small; too small to judge whether a pitcher is performing at his true talent level. Why is this important?

A pitcher’s volatility level is rather high, even for above average pitchers. Meaning a pitcher’s performance fluctuates a lot from game to game. Let’s look at Penny’s and Smoltz’s debuts with their new teams:

Penny for the Giants: 1-0, 8.0 IP, 5 H, 0 R, 2 K, 1 BB, 0.00 ERA, 0.75 WHIP

Smoltz for the Cardinals: 1-0, 11.0 IP, 7 H, 1 R, 15 K, 1 BB, 0.82 ERA, 0.73 WHIP

Now those are stellar numbers. See the fluctuation? I wouldn’t be surprised if either is able to ride this stretch for another 3 or 4 starts. If they did, it would help bring them back to numbers that coincide more with their career averages.

To further my case, let’s look at two pitchers: Tim Lincecum and Joe Blanton. One is the reigning Cy Young winner (an award for best pitcher in the league), the other is known as a number 3 starter, an average pitcher. Their ERA’s differ by more than a 1.50 (2.33 vs. 3.88 respectively). By finding the standard deviation of runs given up by the pitcher by game, we can see how volatile their performances are. Lincecum stands at a 2.86 while Joe Blanton is at a 3.86. What does this tell us?

Despite Lincecum’s status as the best pitcher in baseball, there’s a substantial chance he could give up 2.86 runs more than average, while Blanton could give up 3.86 runs less than his average. This assumes some sort of standard distribution, but you get the point. The probability of Lincecum allowing +2.86 extra runs and Blanton allowing -3.86 less runs is equal to the flipside. So much can happen in a game, a so-so pitcher can outright dominate the game while the stellar workhorse can have an off day. It’s amazing how teams will pay premiums for above average pitchers, even below average ones! Why spend +$10 million for a pitcher who will equally give up either  1 run or 5 runs in one game when you have a minor league spot starter who can guarantee the same performance?

EDIT: Another great example of the volatility we see in pitchers.