What's behind Ubaldo's turnaround?

Over the course of the first month and a half of the season the Indians have found two pitchers to anchor the top of their rotation in Justin Masterson and Zach McAllister.
They also have a lot of options at their disposal to fill out the bottom of the rotation with the likes of Scott Kazmir, Corey Kluber, Brett Myers, Trevor Bauer and Carlos Carrasco.
But the one thing the Indians need the most is that third pitcher in the rotation to be the lynch pin to bring it all together.  Of late, Ubaldo Jimenez has been that guy.
Everyone knows his story. He had a few very good seasons in Colorado before the Indians picked him up in a big trade in July of 2011 and he has underwhelmed since the day he was acquired.
Jimenez got off to another inauspicious start this season when he allowed seven runs in two of his first three outings. It looked like he hit rock bottom as an Indian in his start against the Red Sox on April 16th when he lasted just 1.2 innings and allowed seven runs on two hits and five walks.
To his credit, Jimenez did not cave in and has since turned his season around. Over his last five outings he is 3-0 with a 2.83 ERA and the Indians have won all five of the games he has started. Things have really fallen into place his last three outings as he has allowed just four runs in 16.2 innings and has totaled 25 strikeouts thanks to three straight games of eight of more strikeouts.
The turnaround has come thanks to the work he and Indians pitching coach Mickey Callaway have put into his side sessions and in the video room to try and get his mechanics ironed out. They appear to have found something as Jimenez has been able to more consistently repeat his mechanics, which in turn has drastically improved his command, location, and the quality of his stuff.
Amazingly, it may really be that simple.
With improved and more consistent mechanics, Jimenez is close to the pitcher he was in 2009 and 2010 with the Rockies. The velocity is nowhere close to what it once was, but he is striking out almost two and a half more batters per nine innings this season as he has a 9.7 K/9 this season compared to a 7.3 K/9 last season. He is also putting the ball on the ground at a more consistent rate as he has a 49.5% groundball rate this season compared to 38.4% last season.
The much improved strikeout rate and increase in his groundball rate show that Jimenez is getting more swing-and-miss with his stuff and he is better locating everything down in the zone.
On top of the improved mechanics, Jimenez has also changed up his repertoire and pitch sequences.  Check out his pitch type usage this season as compared to 2012 and in his career:

Jimenez is throwing fewer fastballs this season, by far the lowest percentage in his career. His fastball is only averaging out at 91.5 MPH this season, which is actually the lowest in his career and down a full mile-per-hour from last season when he averaged 92.5 MPH.  With his lack of velocity, the Indians and Jimenez have made the correction to not feature his fastball so much and instead rely more heavily on his deep mix of quality secondary offerings.
The result has been a bump in the usage of his top two secondary offerings: his slider and changeup.  But the biggest change is how he has tabled his curveball this year in favor of his splitter as his main fourth pitch. The splitter is a pitch he has rarely thrown in his career (1.4%) but he is throwing it almost 10% of the time now and it may help explain why he has seen his strikeout rate jump this season.
There are still some questions as to whether Jimenez’s performance over the past month is the real deal and he is back on track, or if it is just a mirage. Time will tell on that, but for now, he looks to be a formidable option for the Indians in the middle of the rotation and could be one of the biggest keys to the Indians’ success this season.
They need that lynch pin, that guy in the middle that brings the rotation all together, and right now Jimenez is starting to look like that guy.