Justin Masterson was a disaster waiting to happen for the Red Sox until that disaster actually happened. His earlier starts hinted at trouble, but it's come on hard in his last two, in which he's given up more homers (three) than he's struck out batters, and walked seven, and did it all in fewer than seven innings of work. Now, there is at least a temporary end to this in sight, as Masterson won't make his next start while the Red Sox figure out if he needs to go on the disabled list for fatigue.
There is a chance that Masterson is either dealing with the fallout from an injury or is just straight-up tired -- he's looked worse as the season has gone on -- and that it's messing with his control and velocity. The Red Sox are right to try to find the answer to this through rest, maybe some time on the DL, and then a rehab assignment to see if Masterson does have anything left to offer. In the meantime, the Red Sox can start someone like Steven Wright, or Eduardo Rodriguez -- who threw 79 pitches for Pawtucket on Wednesday morning -- if they want to hasten his ascension to the majors, and attempt to give themselves a chance to win during Masterson's turns. Wright is more likely, as they could always call Rodriguez up for the second turn through the rotation rather than risk pitching him on three-days rest.
Don't be surprised if the Sox don't bother making a firm decision on Masterson and the DL for a few days. They can move Steven Wright, who threw 5-2/3 innings in relief of Masterson on Tuesday, to Triple-A immediately if they need to bring up another reliever, and then recall Wright on Sunday by placing Masterson on the DL. That will get the Sox around the 10-day waiting period after a demotion for Wright, and also give the Sox, their doctors, and new pitching coach Carl Willis a few days with Masterson before sending him off to the DL to be left alone for a couple of weeks.
Conversely, they can just put Masterson on the DL when they need to call up that extra reliever, and go right ahead and hand Sunday's start to Wright. Either way, it seems a stint on the DL is imminent, and the real question is whether or not it will do anything to salvage Masterson's season.