"It really goes back to consistency in delivery," said pitching coach Carl Willis. "With the inconsistencies, I know it's no secret -- hitters know what's coming. He's worked on it extensively during bullpen sessions, dry work periods, makes progress, shows the ability to make those adjustments.
"However, when the game begins, the game situations start and his focus gears more toward the attack of the hitter, the old habits resurface. It's not from lack of effort on his part. It's just a bit much for him to accomplish at the Major League level where hitters can look for inconsistencies and make adjustments."
The Red Sox don't need a fifth starter until Tuesday, but Red Sox manager John Farrell might want to plug someone in by Sunday, which would have been Rodriguez's regular day to pitch. Left-handers Henry Owens and Roenis Elias are logical candidates. Righty Aaron Wilkerson is having a strong year for Pawtucket, but he is not on the 40-man roster. Reliever Pat Light was recalled from Triple-A for the second time this season and took Rodriguez's roster spot on Tuesday night.
What the Red Sox are most concerned with is figuring out a way to get Rodriguez (1-3, 8.59 ERA in six starts) to function at a similar level as last year, when he went 10-6 with a 3.85 ERA in 21 starts.
Complicating the matter is that Rodriguez has completely lost the feel for his slider and has become a two-pitch pitcher (fastball and changeup).
"It is a pitch we want to see him use more," Willis said of the slider. "It is a pitch he has flashed in the bullpen. Obviously he has had a lot that has gone on this year with the injury to the knee and the rehabilitation period. So much focus is on the knee, on the lower half. How it feels getting his lower half getting back engaged in his delivery.
"I think he lost a little bit feel for that slider. Again, he shows it in his bullpen [sessions]. He actually threw a few more last night. Some of the action on some of them was what we were looking for, but the command wasn't quite what we were looking for. So it's the pitch we're still looking to get back. He shows the definition to the pitch at times. It's just not consistent."
Despite the lack of success in their starting rotation of late, the Red Sox will give Rodriguez as long as he needs to make the necessary fixes.
"That's going to be a start-by-start situation. How he solidifies the adjustments that are required, so I don't have a timeframe on how long that's going to be," said Farrell. "I can tell you this: Every start that he's made here and even prior to coming back from the rehab assignment, there's been work that's been ongoing and sometimes that hasn't even solidified to this point. So I'm not saying that's going to be a timeline similar, but to suggest this is a one-start situation would be a little aggressive."