Jimenez began the year in the starting rotation and has performed well in his four outings. At this early May juncture, he's been the team's best starter. In 22 2/3 innings, Jimenez has a 1.59 ERA (3.57 FIP, 3.01 xFIP) -- far superior to his 2014 ERA of 4.81 (4.67 FIP, 4.48 xFIP). His strikeout rate (one of the earliest things for a pitcher to stabilize) of 8.74 is slightly above his career average (8.28), while his walk rate is down (3.18; career 4.16). Walk rate requires a larger sample size to stabilize, but limiting the number of free passes will go a long way to determining Jimenez's success.
At the moment, Jimenez is first among all O's pitchers in bWAR (0.8) and tied for first (with Zach Britton) in fWAR (0.4). Sure, the Orioles have only played about 12% of their games. But there are still some interesting things going on with Jimenez.
One of them is the growing disparity of Jimenez's fastball usage. Early in his career, Jimenez opted for many more sinkers than four-seam fastballs, and then for a few years in the middle of his career, he threw both about the same. But his sinker usage has been trending up since 2013, and if he continues throwing sinkers about 50% of the time, it would be a career high.
Despite throwing a plethora of sinkers last season, Jimenez not only didn't locate the pitch well, but it also didn't lead to a bunch of grounders either. Jimenez's groundball percentage steadily declined from 2008 to 2012 (from 54.4% to 38.4%). It rose to 43.9% in 2013 but dropped again last season (41.3%). And yet, right now it's 67.3%, which leads all starting pitchers. It's obviously not going to stay that high, but a groundball rate between 45% and 50% wouldn't be unreasonable, especially if he's locating his pitches and throwing his sinker lower in the zone (though not too low). It's also worth mentioning that Jimenez's current BABIP is .157 (third lowest among all starters). His career mark is .290, so more hits are going to start dropping in. But ground balls don't leave the ballpark, and fewer runners are going to score on those hits if Jimenez isn't walking 5.5 batters per nine innings.
Jimenez's velocity has been trending down for years, and that's played a part in the decrease of swings and misses on his two fastballs and slider (three of the four pitches he throws the most). But Jimenez could be seeing a resurgence in whiffs when he throws his splitter:
The whiffs against his splitter took a dive last year after trending up for a couple seasons. Of the pitches Jimenez throws the most, the splitter has generated the highest career whiff rate (16.4%; 12.1% vs. slider, 8.4% vs. four-seamer, and 5.8% vs. sinker). One problem for Jimenez last season was that he threw the splitter too low, so opposing batters weren't chasing it as often. So far, he's rectified that issue, and getting ahead in the count more often has been beneficial.
Some additional factors could also be playing a part in Jimenez's improvement. Since he signed his contract the previous offseason, he didn't have to worry about getting hurt this offseason and ruining the opportunity to get paid. So he could ramp up his workouts again and not have to worry about an "accelerated program." The Orioles also signed Ramon Martinez as a special assignment pitching instructor, and he worked with Jimenez in the spring. Martinez may have helped Jimenez fix some mechanical issues:
There's no secret Jimenez's delivery is unconventional and it takes just one misstep for him to get out of whack. On video, Martinez showed him how his back foot was collapsing, which prevented him from staying on top of the ball. Also, his hands were coming too far back before he threw, unlike the smoother delivery he had in Colorado.
"It's all about the mechanics," Jimenez said. "Before my mechanics were so messed up that I couldn't have good command of the fastball. When I fell behind in counts, I couldn't come back. I've been working with Ramon in spring training [to] get my mechanics right to where they're supposed to be, staying tall, breaking the hands early so I have time to catch up my arm. That's why everything is good right now. My mechanics are ready. Everything is feeling the way it's supposed to."That piece is worth a full read and is even more intriguing considering how well Jimenez has pitched. Perhaps Martinez provided Jimenez with what he needed to succeed again. Maybe Jimenez would have pitched better anyway. Maybe it's a combination of both. But even though Jimenez has looked pretty good so far, his next challenge is to keep it going.