It was revealed a week ago that Carl Pavano's shoulder was hurting and that the team had him undergo an MRI for precautionary measures.

Fortunately for the already thin pitching staff, the MRI showed nothing more than inflammation and, in preventative efforts, the Twins eased up on their workhorse, limiting his pitches and allowed him to miss the recent series in Detroit to have some soft-tissue therapy on his shoulder. The hopes are that by lightening his load, Pavano will heal and not require a cortisone shot following his next start.

Since the beginning of the season, Pavano's velocity drop has had team officials concerned. While the tests showed no significant injury, the big right-hander admitted that he feels that he cannot get proper extension on his pitches and his results suggest there may be something to that.

While his peripheral numbers are actually a slight improvement over his 2011 campaign – his strikeout rate is up, his walk rate is down – his ability to generate ground balls has dissipated over the course of the season. Currently holding a 44.2% ground ball rate, it is his lowest amount of turf-killer since the year he came over to the Twins in '09. Because hitters are able to elevate the ball, he is allowing home runs at a higher clip – going from 0.93 home runs per nine innings to 1.29.

Through his first four starts of the year, Pavano pitched like business-as-usual. He was able to miss bats (8% swinging strikes) and induced more grounders than fly balls (1.18 GB/FB). From his April 22 start against the Royals onward, likely when the Twins began to limit his pitch count, Pavano was a different pitcher. Hitters were making outstanding contact (just a 3% swinging strike rate) and the ground balls dried up (0.65 GB/FB).

Outside of his fastball's velocity, the biggest causality of his sore shoulder has been his second most used pitch, his changeup, and one of the reasons the grounders have become fly balls.

In 2010 and 2011, Pavano's change was one of the game's best according to Fangraphs.com's Pitch Value. His 18.1 runs above average on the pitch was tied for ninth-best in that span, placing him with such change artists as Felix Hernandez, James Shields, Shaun Marcum and Ricky Romero. This season, his change-up is now 2.6 runs below average, making it one of the bottom-dwellers in that category.

In theory, a change thrown with good differential and down in the zone should induce plenty of weak contact as hitters find themselves unable to hold up and turnover on the pitch. For example, a year ago his changeup was able to get a ground ball on 51.6% on all contact (including fouls, home runs, etc) which is a very strong rate. Comparatively, this season, Pavano's change has only incited grounders just 39.3% - meaning opponents are squaring up on his secondary pitch. What's more is that in 2011 he was able to get a swing-and-miss on 27% when opponents swung but that has declined to 15% in 2012.

As I speculated following his first start, the decrease in his fastball's velocity was going to adversely affect his change-up as the speed differential closes. Baseball Info Solutions' pitch charting states that while his fastball is down (from 89 to 86 miles per hour) his change's top speed has also decreased (from 80 to 78 miles per hour). This means the differential has not been that substantial at all. Pitch F/X, on the other hand, shows that Pavano's vertical movement on his change is quite different. As I discussed in my analysis of Jason Marquis at Twins Daily on Wednesday, research has shown that the optimal place to get the most ground balls is between 0.0 inches and 3.0. The previous two seasons, his changeup had a vertical finish of 2.0 and 2.7, meaning it was down in the zone. This season it is up to 3.8.

In laymen's terms, Pavano's changeup has been up in the zone more frequently therefore resulting in fewer grounders and swing-and-misses on that particular pitch.

Another factor that might explain the in-season drop in grounders and missed bats is the sudden disappearance of his slider. According to Pitch F/X data, in his first four starts he threw his slider 45 times (11% overall). In his last four starts, he threw it just 8 times (3% overall).

His sore shoulder, his inability to get extension and a lack of feel for the pitches may contribute to why he has not spotted his changeup well and why he has ignored his slider as of late. Will the rest and rehab approach prove to be fruitful? Answers will be provided on Saturday when Pavano makes his regularly scheduled start in Milwaukee. Attention should be paid not only to the radar gun readings but also to the performance of his secondary pitches.

Over at TwinsDaily.com:

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