June 13, 2008

Prospectus Today

Natural Ebb and Flow

by Joe Sheehan

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Two left-handed pitchers, teammates in fact, and their work since April 25:

    GS    IP   ERA     K   BB   HR   OPS    W-L
A   10  73.1   2.09   73   14    5   614    4-5
B    8  50.1   3.93   41   12    4   772    6-1

It's pretty clear which one of them has pitched better, and in fact, it's the one you would have expected to pitch better at the start of the year. It's the one who won a Cy Young Award, the one who pitched in the All-Star Game last year, the one whose impending free agency has GMs gripping their checkbooks in anticipation. The other guy? He was in the minor leagues 10 months ago, considered a disappointment thanks to 2006 and 2007 seasons that didn't measure up to his 2005.

Those stat lines don't tell the whole story, though. Because prior to April 25, C.C. Sabathia had the worst four-start stretch of his life, throwing just 18 innings and allowing 27 runs, with a 14/14 K/BB and an 1170 OPS allowed. At the same time, Cliff Lee was putting together maybe the best four-start stretch of his own career: 31 2/3 IP, 29/2 K/BB, 0.28 ERA. Those four starts, those three weeks of baseball, mean that the perception of the two players' 2008 seasons, and their relative values, are set in a way that may be impossible to change, even though the values of the two players are converging, even perhaps crossing. Even though those three weeks are the only time that Lee has been better than Sabathia in the last three years. Run support is part of the perception problem as well-Sabathia has just a 4-5 mark during this stretch of outstanding work because the Indians have scored two runs or fewer in seven of his last 10 starts. The Indians have scored fewer than three runs just once in Lee's last eight outings.

Even as I write this, I'm not entirely sure where I'm going with it. Certainly, I want to make the point that C.C. Sabathia is, seasonal stat lines aside, better than Cliff Lee. I expect that by the end of the year, the big lefty will have produced more value, as measured by whatever metric you care to use, than his smaller teammate has. That's not a knock on Lee, whose command of his fastball and decision to pound the strike zone with it have put his career back on track. As you can infer from above, though, the extremely low batting average on balls in play that was a contributing factor to his hot start has meandered back up to normal-it's .298 for the season now-and has brought his rates and his ERA up with it.

There are other issues in play, though. I remember how much attention we paid to Sabathia's problems in April, how we had to find a reason for them. I wrote a column, I talked about him on "Fantasy 411" and "The HotList," I answered questions on the radio. There was speculation about Sabathia's health, given his 2007 workload. There were questions about his head, about whether his impending free agency was causing him to put pressure on himself. There were questions about his mechanics.

As it turns out, the null hypothesis-there's nothing wrong with Sabathia that a few more starts won't fix-was the correct one, and looking back, I'm annoyed with myself for not making that point more forcefully. We've become so attuned to short-term variations in performance, likely a mix of fantasy baseball considerations, the wide availability of information about baseball, and the need to fill Web pages and column inches and airspace with news and opinions. Baseball hasn't changed, though. It's a game in which player performance varies widely around a mean, and we've all taken to assigning far to much meaning to that variation. Cliff Lee pitched better than C.C. Sabathia did in the season's opening stanza, and he also got a bit more lucky, but he wasn't suddenly a better pitcher than Sabathia. Short-term performance isn't the same thing as ability.

Maybe that's the important point. Ability changes, of course, but it's only in looking back over a career that we can see when it did, because it generally changes slowly. Consider Jason Giambi, who twice in the past three Mays has been targeted for either a trip to the minors or a release. In fact, his ability has been declining slowly, but he's still a productive player, and his performance after slow starts in 2006 and 2008 serves as another argument against overreacting to two weeks, four weeks, six weeks of baseball. Frank Thomas is hitting .319/.417/.516 as an Athletic. Barry Zito has a 4.54 ERA since April, with three quality starts and three other decent ones. The Royals are 20-39 since the season's first eight games.

C.C. Sabathia is pitching circles around Cliff Lee.

We have to do a better job of making the point that short-term performance is less often an indication of some change in player ability, whether due to development, age, injury or other factors, and more often just the natural ebb and flow of the game showing itself. This applies to teams as well, where "hot" and "cold" streaks are imbued with far too much meaning. They are simply the teamwide expression of that natural ebb and flow. Baseball isn't like any other sport in this regard, and it's time we start respecting that complexity.

Joe Sheehan is an author of Baseball Prospectus. 
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