Jeremy Jeffress had a circuitous route to the majors that started and culminated with the Brewers, but there were other stops along the way. The Brewers drafted him in 2006. Then he was shipped with others to Kansas City in the trade that brought Zack Greinke--and he who shall not be named--to Milwaukee. Later he spent some time with the Blue Jays only to be DFA'd. The Brewers then plucked him out of minor league free agency mid-2014. I don't think I was alone in expected little to nothing from Jeffress and I know I'm not alone finding pleasure in how wrong I was.
Thing about Jeffress is that while his raw stuff is good his command was always well below average. He has strong velocity on his fastball and his curveball is a legit pitch. But when hitters know you can't hit the strike zone they'll just wait until they either draw a walk or get a pitch to crush. This was definitely evident during his short stints with the Royals in 2011 and 2012 when his walk rate was 16.4% and 17.8% respectively. His walk rate with the Blue Jays in the first half of 2014 was 14.8%.
Naturally I expected this to be a continuing trend but instead Jeffress, presumably with the help of the Brewers coaching staff, was able to reverse the trend instead. Last year his walk rate was 6.1%. This year his walk rate was 7.7%. That is exactly league average for 2015. I don't know what led to this change in Jeffress but it's been drastic and helped him to become a very good reliever.
His ground ball rate was extremely good as well. His 58.2 GB% ranks 18th out of all 137 qualified relievers. This is a genuine skill of his too. His career ground ball rate is 57.4%. His ability to keep the ball on the ground all helps him keep it in the park. This year he had a 0.66 HR/9 which was actually the second highest of his career. Over his entire career--149.0 IP--he has a 0.48 HR/9 so we're again looking at a repeatable skill.
His strike out rate was above league average this year as well--23.5% vs 20.4%. You combine those three things and you get a 2.65 ERA and 3.22 FIP. That's really very good and it bodes well for the future because all signs point to his skill set being real and repeatable.
Another perhaps sometimes overlooked ability of a reliever is endurance. Jeremy Jeffress threw 68.0 innings in 72 appearances. That ties him for the 18th most appearances by a reliever. It also puts him in the top 30 for total innings pitched.
Jeremy Jeffress was a really smart pick up by Doug Melvin and the Brewers last year that should continue paying off for several more years to come. He won't be a free agent until after the 2019 season. If he can continue producing like he did this year he has "closer potential." Pretty good for a guy that was released by the Blue Jays just 18 months ago.
Statistics courtesy of FanGraphs