After losing David Price to a trade with the Tigers and Alex Cobb to injury, The Rays needed Chris Archer to step up this season. Chris Archer then proceeded to step up this season. He’s carrying a 36 ERA-, 80 FIP-, and 69 xFIP-. His K-BB% is 23.6, better than his career mark by 10%. Obviously his numbers have improved. But it’s April, and the question everyone asks in April is are the improvements sustainable. Real improvements are the results of real changes, so let’s look for real changes.

One of the reasons for Archer’s success this year has been due to his ability to limit walks, which before had been a bit of a problem for him. Coming into the season he had a Zone% of 43.1 which is a tad below the league average. This year, that figure has increased to 54.4%. If you throw the ball in the zone more, you’re gonna get more strikes… more strikes means fewer times behind in the count… etc. You get the idea; good Zone% is good. But it’s not just that he’s throwing more pitches in the zone; Archer is allowing less contact on the pitches he throws there. Archer’s Z-contact rate has dropped by 4% from last year. So, to sum it up, Archer is throwing more pitches in the strike zone and hitters are making less contact when he does. This explains why Archer is getting more strikeouts and conceding fewer walks. What it doesn’t tell us is how he’s doing it. To figure that out, we have to look at his pitch selection.

According to the PITCH F/X data on FanGraphs, Archer was a two-seam-first pitcher last year – throwing the pitch nearly 47% of the time and his four-seamer only about 20%. The year, Archer’s increased the usage of his four-seamer by over 23%, dropping his two-seam rate to only 12%. This change is important because, thanks to work done by Jeff Zimmerman, we know that four-seam fastballs tend get strikeouts more often than their two-seamer cousins do. The four-seam isn’t the only pitch he’s increased usage for either: Archer’s slider rate has gone up to about 39% after sitting a little below 29% last year. Once again, this is good for strikeouts. Because, not only do sliders have the highest SwgStr% among pitch types after splitters, but the increase indicates Archer is more confident in his slider, which could imply that the slider has improved. You can say the same thing about the four-seam.

If you were looking for indicators that Chris Archer’s improved numbers have a level of sustainability, there they are. Those are real changes, from a real pitcher, playing real baseball. The Rays are gonna need an ace-level performance in their rotation this year to help alleviate the loss of David Price and the temporary one of Alex Cobb. It’s beginning to look like Chris Archer is the man for the job.