Gerrit Cole had a 3.50 ERA and 1.21 WHIP while striking out 8.4 batters per 9 in five seasons with the Pirates.
Gerrit Cole had a 2.68 ERA and 0.96 WHIP while striking out 13.1 batters per 9 in two seasons with the Astros.
So what changed after he left Pittsburgh?
Cole's velocity with the Astros ticked up a bit and he changed the way he attacked hitters with his fastball. He also changed his release point. But whispers about how the Astros help their pitchers (specifically when it comes to using substances on the baseball to improve grip and spin rate) have dogged Cole and others who have had tons of success after arriving in Houston.
Those whispers about the Astros are due in part to Reds pitcher Trevor Bauer, who has called out Houston in the past while also taking what appears to be a swipe at Cole while questioning the way the Astros use foreign substances.
One substance Cole and others have been accused of using is Pelican Grip -- a pine tar and rosin blended grip enhancer.
Speaking with Joel Sherman of the New York Post, Cole -- whose spin rate went from below average to elite after joining the Astros -- denied that the Astros were better at creating a sticky substance for pitchers to use on baseballs and/or at teaching pitchers how to employ using those substances.
"(Spin) is a skill that (Astros pitching coach) Brent (Strom) and those guys over there have great tips on what maximizes spin. Period. They just do," Cole told Sherman. "Brent was forward-thinking in the sense the Cardinals wanted to go east and west and he wanted to go north and south. … So finally he gets over to a new team in Houston, he gets control of the reins and people are going north and south and they think it is a new invention. It is not a new invention."
It should be noted that many pitchers use substances to improve their grip, with many batters looking the other way because they would rather pitchers be able to control where the ball is going.
Starting this season, though, MLB will be cracking down on pitchers who violate Rule 8.02, which prohibits pitchers from doctoring the baseball with anything outside of the legal rosin bag.
How that impacts pitchers throughout the league remains to be seen, but it is definitely something to keep an eye on in 2020.