Rubby De La Rosa, RHP
De La Rosa is now in the majors with Clay Buchholz placed on the disabled list, so including him here is cheating a little. Rubby will be starting for the Red Sox presumably until Buchholz sorts out what's wrong with him -- be it physical, mechanical, mental, whatever -- so we might as well take his turn in the update to gauge his readiness for that, though.
It's my opinion, based on everything we've seen from Rubby De La Rosa since he came to the Red Sox, that he's going to end up in relief. He's got dominating stuff, but he tends to be inefficient and inconsistent too often, and it could end up keeping him from a career as a starter. With that being said, the Pawtucket rotation isn't so full that he should be shoved into the bullpen just yet, and obviously neither is the major-league one since there's space for him right now in Boston. Seeing if De La Rosa's recent success, in which he's rediscovered some of the swing-and-miss you'd expect from him, can keep going in Boston makes sense.
At the same time, don't set those expectations too high: De La Rosa's walks have also climbed, and while he's still inducing lots of grounders, it's nowhere near the extreme rates of his start to the year. He averaged just over five innings per start in May, which was actually a little worse than his already worrisome low totals in April: he might work as a fill-in while Buchholz hits reset, but De La Rosa's level of success in Pawtucket doesn't make me feel overly confident in an extended quality stretch as a starter in the bigs.
The fan side of me would love to be wrong about this, but wanting something doesn't make it true. That part's on De La Rosa.
Bryce Brentz, OF
Bryce Brentz was placed on the DL 10 days ago retroactive to mid-May thanks to straining his hamstring. With this being the case, not all that much has changed since last we checked in: he's still striking out too much, and while the walks are there, he hasn't been putting the ball in play often enough to support it.
It's still early in the season, and he's had a few weeks cut out from underneath him due to injury, so don't panic too much. He's 25, though, not a baby, and this is his second go-round at Triple-A, so at some point he's going to have to do more than show flashes of becoming a big-league outfielder. He'll get his chance again once he returns from injury.
Travis Shaw, 1B
Shaw just got here, so he's only got the four games at Pawtucket under his belt. There would be little to say about his performance if only because of that, but we can tell you what we will be looking for in his Triple-A performance. Shaw had only recently changed his two-strike approach, as he finally learned how to balance patience with aggression in order to unlock actual plate discipline: previously, he had been a little too passive, or a little too Lars Anderson if you want to cut to the chase. Seeing if he can maintain his ability to draw walks, limit strikeouts, and hit for power is going to be one of the keys for the rest of his season.
The other major one might not show up in his stat line as easily, as it involves Shaw's bat speed. If his strikeouts shoot up and he has a hard time hitting for power -- more so than in the initial adjustment period you would expect after a promotion -- then it's time to start wondering whether International League pitchers are challenging him with pitches he can't catch up to in places that make it even harder. It happened to Anderson, it happened to Ryan Lavarnway: Shaw might have the skills to avoid making that a trio, but we won't know until we see him respond to the challenge.