The Amazing Weaver and his disappearing fastball

The diminishing velocity on Jered Weaver's fastball has been both a terrifying and fascinating storyline for Angel fans the last few seasons. While Weaver has never pumped in fastballs harder than 90 MPH, instead relying on elite command of four quality pitches, his velocity has steadily declined to the point that his fastball is clocking in slower than the average big league change-up. Last season saw the steepest decline, dropping from 86.3 MPH in 2014 down to 83.3 MPH. So far this year, Weaver's fastball is down to an average of 82.0 MPH.

That drop in velocity has led to a similar decline in his strikeout rate, a dismal 5.63 K/9 this year. This means more fly balls than ever, which leads to more home runs allowed. Add it up and you get a replacement-level 5.55 FIP (fielding independent pitching), thought by many to be the best indicator for a pitcher's future success (or lack thereof). Up until last season, Weaver has notoriously out-performed these performance indicators. Somehow he is pulling that trick again this season, with a 3.86 ERA thus far.

How is he doing it? By using his dead-fish fastball as little as possible. Weaver is throwing his fastball just 43.7% of the time, the 12th fewest among qualified starters. One and two on that list are R.A. Dickey and Steven Wright, both knuckleballers. Six of the other names on the list throw cutters, which are essentially just another type of fastball. Two of the other names, Masahiro Tanaka and Hisashi Iwakuma, throw a disproportionate amount of splitters, which is the norm for many Japanese pitchers. That leaves only Felix Hernandez ahead of Weaver, throwing 43.3% fastballs, relying heavily on his change-up (25.6%) and curve ball (24.1%).

What separates Weaver from Hernandez and other pitchers with similarly-low fastball usage this year (besides velocity, of course) is how evenly Weaver distributes all four of his pitches:

While not fooling anyone, Weaver is keeping the batter guessing with every pitch. Opposing hitters are tracking his big slow curve especially well, with the White Sox being the lone team this season to bat under .500 against the pitch during his four starts. He is acquitting himself with his change-up and slider, pitches less discernible from his BP fastball.

Can Weaver continue to survive in this league using these magic tricks? Looking at last season, the only pitcher with a similar distribution of four pitches was Zack Greinke, who of course throws a 92 MPH fastball to complement his off-speed stuff. Mark Buehrle averaged a Weaver-esque 83.4 MPH fastball last season, with a 79 MPH cutter that he threw 15.7% of the time, essentially doing the job of Weaver's slider. The veteran lefty won 15 games with a 3.81 ERA while performing a similar high-wire act, so it is not impossible.

Jamie Moyer survived for years throwing 82 MPH, but was quickly chased from the league once that average fell down to 79 MPH in 2012. If Weaver's velocity falls any further, he will likely be done, as well. In the meantime, as long as he can command his four pitches, he should be able to keep the Angels in games as well as any other back-end starter around the league, giving Angels fans one last hurrah for the shaggy-haired hometown boy.

All data courtesy of Fangraphs.com and Brooksbaseball.net.