Tim Lincecum’s Aging Curve
Tim Lincecum has been one of the most interesting players in the majors since his rookie year in 2007. This is partly due to the fact that he possesses a formidable fastball despite being listed at only 5’11” and 163 lbs. It’s also partly due to his unorthodox windup, which also happens to be the reason he is able to throw harder than one would think. And of course his signature hair-style that makes him look more likely to appear on the set of Wayne’s World than a pitcher’s mound. To the chagrin of Giants fans, and probably the majority of baseball fans alike, Lincecum has struggled so far this season. His ERA is 6.09, and his WHIP of 1.57 is the highest of his career.
Lincecum’s ERA is inflated a bit by a BABIP of .330, and has only stranded 60.5% of base runners. His FIP of 3.89 is solid, but it’s significantly worse than his career rate of 2.99. So although he hasn’t been quite as terrible as his ERA would make you believe, he hasn’t been performing at the CY Young level that we are used to seeing. Looking deeper into the numbers, there are some underlying problems that may explain the drop off in performance. For starters, his walk rate is up 2.6% over his career rate, and his strikeout rate is down 2.6% over his career. This statistical symmetry implies that 2.6% of the batters Lincecum would normally be striking out are being given a free pass instead. On top of that, his ground ball rate is down to 41.5% from 47.9% last season. Batters have also been hitting more line drives (26.3%) off of Lincecum than in any previous seasons. Not only is Lincecum walking more batters this year, but batters are squaring up the ball at a more frequent rate.
When looking at his pitch data, we see some issues that could be the cause of Lincecum’s problems. His fastball velocity is down 2.1 MPH from last season, and perhaps even more alarming, his least effective pitch according to pitch values has been his changeup (-6.9 wCH). This is especially problematic because Lincecum’s Bugs Bunny changeup had been his put-away pitch in seasons past. In his last four seasons, his changeup has averaged a 16.4 wCH. It is entirely possible that the lack of fastball velocity is directly correlated with the decline in his changeup’s effectiveness. After all, the changeup is a pitch that is used to fool hitters into believing it is a fastball. If you shave a couple miles per hour off the difference between the two pitches, that is going to make for a significantly less effective combination at the major league level.
There is no way for me to know what is causing Lincecum’s fastball velocity to drop. But it is certainly easy to point to the fact that he has already thrown 1,142 major league innings (including playoffs), despite this being only his sixth season. In the previous four seasons, he has averaged well over 229.2 innings per year. However, it may simply be that pitchers start to see a drop in velocity at around Lincecum’s age (28). This chart on pitchers and their aging curves from Fangraphs seems to suggest that Lincecum has simply reached the age at which he may start to lose some zip on his fastball. The fact that he has thrown so many innings may even accelerate the aging curve for Lincecum, possibly leading to the drop in velocity we are seeing this season.