Jeremy Jeffress threw 10 innings for the Brewers back in 2010 when he was still a reasonably well-regarded Brewers prospect. The following offseason he ended up being an important part of the package that went to Kansas City for Zack Greinke. I wrote a short post back in late 2010 to give something of a first look at Jeffress's stuff. My general prognosis then was that he could probably be an effective major league reliever by just relying on his big fastball and occasionally mixing in his curve to keep hitters off balance. At the time, people still saw him as a possible starter down the road. I said that probably wasn't going to happen without him adding some additional weapons.
We don't have a ton of information about Jeffress's pitch selection preferences in the big leagues but it's potentially worthwhile to at least see if much of anything has changed since those 10 innings in '10. The book on Jeffress hasn't changed much since then-- great stuff, command problems, and a lack of complementary pitches to the fastball were all that were preventing him from being an effective major leaguer. It was true while he was coming up through the Brewer system and it's true now that he's been bouncing between organizations as a journeyman reliever.
In the 2010 cup of tea, Jeffress threw his fastball 80% of the time, averaging about 96.7 mph. Almost all of the remaining pitches were curveballs, and he mixed in 7 changeups. In 8 innings in the big leagues this year, the fastball percentage is closer to 82%-- 107 out of 131 pitches have been fastballs. He's averaging about 97.3 mph, slightly better than his 2010 average. He also seems to have modified his grip somewhat to generate more movement. Pitch f/x categorized his main fastball as a straight 4-seamer then but it looks a lot more like a sinker now. Also interesting is that he appears to have canned the changeup, or at least not used it in his limited opportunities to impress the higher ups in Major League appearances this year. He's only thrown one pitch on the year between the velocity clusters of his fastball (upper 90s) and his curve (around 80).
The process for Jeffress has been tweaked, but once again the prognosis is essentially the same. If he can deploy his curve just enough to keep hitters honest, his fastball velocity is a good enough weapon that he can be effective at this level. There are only about 15 other pitchers in MLB that are capable of throwing as hard as he can. We haven't seen enough of him this year to get a good handle on his how good results of certain pitches are, but as we saw in yesterday's game against the Cardinals, continuously pumping fastballs out over the plate is not a recipe for success even if they're coming in at 97 with movement. On the year, Jeffress has yet to throw a curveball when he is behind in the count. Hitters notice things like that.
I'm pulling for Jeremy, but looking at him as the #1 right-handed option behind K-Rod in the pen right now is not putting him in a position to succeed. There's reason to think he's better-adjusted to his role as a reliever now than he was in 2010, but the problems we identified then haven't exactly disappeared.