Astros: Zack Greinke sustains success through evolution

Houston Astros pitcher Zack Greinke has managed to remain successful despite changes to his arsenal.

When the Astros acquired Zack Greinke at the trade deadline in 2019, the excitement was palpable among the Houston faithful. His addition gave the team a third ace alongside Justin Verlander and Gerrit Cole, and it got them just a few outs shy of another World Series championship.

Greinke, however, is an entirely different kind of pitcher than Verlander and Cole. In fact, he’s an entirely different kind of pitcher than he was earlier in his career. While Verlander has defied nature and maintained his elite velocity through his mid-30s, Greinke has adapted to the loss of zip on his fastball and managed to remain at the top of his game.

To highlight this evolution, I’ll compare his 2019 season, in which he won 18 games with a 2.93 ERA at age 35, and his 2009 season, in which he won 16 games with a 2.16 ERA and won the AL Cy Young Award at age 25.

Peripheral Stats

As expected, Greinke’s strikeout rate was higher in 2009. He struck out 9.5 batters per nine innings, totaling a career-high 242 strikeouts in 229.1 innings. In 2019, he fanned 8.1 batters per nine, which is still a solid rate for someone who doesn’t rely on strikeouts as much.

But his walk rate also declined. He walked just 1.3 batters per nine innings in 2019, down from 2.0 per nine in 2009. His home run rate in 2009 was abnormally low at 0.4 per nine, but his 2019 rate was still good at 0.9, despite the barrage of home runs across the league.

Although his WHIP was better in 2019 (0.982) than 2009 (1.073), the ERA+ and FIP stats liked his 2009 season better, since he prevented runs more effectively despite allowing more baserunners. Still, his 2019 WHIP was the second-best mark of his career, and his strikeout-to-walk ratio was a career high.