J.C. Linares, OF
After convincingly crushing Double-A pitching, 27-year-old Cuban import Juan Carlos aka J.C. Linares was promoted back to Triple-A, where he spent the little time he played in 2011. He hasn't been there very long, but he's been successful for the most part. His strikeout rate is still low, but he could stand to add a few walks, as his power is down and there's no guarantee he can rely on batting average on balls in play forever. Still, it's a solid reintroduction to Triple-A, and if he can keep it up, then it'll be easier to believe in him as actual outfield depth for the big-league team.
Linares' issues mostly had their root in secondary stuff, as he's a great fastball hitter who hasn't quite adjusted to other offerings yet. More time in Triple-A could fix that problem, or exacerbate it, but we won't know for sure until much more than 91 plate appearances have passed.
Jose Iglesias, SS
Iglesias was hitting well before his injury that kept him out for around a month's time, but since his return, the bat just hasn't been there. The 22-year-old shortstop is hitting .289/.310/.316 in his last 10 games, a rate that's fine in terms of batting average, but otherwise is problematic. The only real positive as of late is that Iglesias has cut down on his strikeouts dramatically -- 16 of his 28 whiffs on the year came in April alone. The problem is that his walks have also slipped, with just six free passes since April's eight.
This leads one to believe that, while he might be hitting pitches better than he used to, he's also been a bit impatient, and isn't allowing the plate appearance to survive long enough to draw a walk or punch out. He needs to discover some kind of balance between this aggressive approach and the more patient one he had been developing, or else there will just be too many holes in his game for him to do much at the plate in the majors. That being said, he's still just 22. With every shortstop added to the system, though, Iglesias begins to look less and less necessary in Boston's future.
Che-Hsuan Lin, CF
Lin, like Iglesias, just can't seem to maintain any kind of consistent offensive production at Triple-A. His May looked like a turning point, as he put together a .299/.415/.373 line, his best showing in months, but since then, he's managed just a 550 OPS in June and is now hitting .296/.316/.352 in July.
Of course, also like Iglesias, Lin has fantastic defensive potential, and still is in line to be a bench outfielder who can pinch run and slot in anywhere in the outfield. But you would like to see a few more months like his May, where he actually looked like he could hold his own in the majors even a little, before you commit too much to his future.