Brian Johnson, LHP
Johnson has only been at Double-A for 54 innings and nine starts, but thanks to his polish and command, all he's done is dominate. He's struck out 7.7 batters per nine, so that's not the reason for it by itself, but that plus his lovely walk rate has resulted in 3.4 times as many strikeouts as walks. He's kept the ball in the park, averaged six innings per start, and kept hits to a minimum.
These kinds of numbers won't follow Johnson forever, as his likely projection puts him as a back-end starter, with a ceiling that's maybe a little higher. He's likely to continue to crush his opposition in Double-A, however, as he's just too advanced for them. Maybe he scuffles a little bit as Eastern League batters adjust to him, but he's further along in his development than most starters in the system, thanks to his time in college -- including the College World Series -- and stint on Team USA.
It's past time to pay attention to Johnson as a legitimate pitching prospect in the Red Sox system, though. The dreams for Allen Webster and Anthony Ranaudo are nice and all (and should exist, as they're talented arms), but they've come at the expense of Johnson, who likely has a better shot at being a major-league starter than two pitchers who have been dogged by questions about command and effectiveness. Luckily for the Sox, they have all of them in one system, so it doesn't really matter if Johnson isn't perceived correctly on the outside. Given the speed at which they've sent him up the ladder, they're well aware of him.
Noe Ramirez, RHP
It seems like it's just about time for Noe Ramirez to get bumped into the Triple-A bullpen. He's thrown 64 innings in relief at Double-A over the past year -- he was promoted to Portland in early July of 2013 -- and has seemingly corrected the home run flaw of last summer, which saw him allow 1.3 homers per nine in 28-2/3 innings of work. It's also worth seeing what he can do at a higher level, as he's Rule 5-eligible this December, and could be plucked from the system by another club at that time. Maybe that's part of the reason the Sox aren't in a rush to send him to Triple-A, as it might just make it even more obvious he could be a useful bullpen piece.
There are questions about Ramirez's future even in that role, though. His command improves after a brief hiccup at each level, as he learns where he should and should not pitch the baseball, but his control is legitimate all the time: he's walked an even two batters per nine in his three-year minor-league career. It's very much a control vs. stuff question: He isn't barely scraping by thanks to this control or anything, but big-league opponents are not the same as those at the levels he's played at. He's passed the tests he's seen to this point, though, and maybe that keeps happening, but it is the big question with him.
Luis Diaz, RHP
Diaz took the rotation spot opened up by the 100-game suspension of right-hander Mickey Pena, and he's done well with it so far. Unsurprisingly, the strikeouts aren't all there, with Diaz picking up eight in his first 14 innings at the level, but the control that's served him well to this point came with him in the early going.
Diaz is likely to relieve if he's to have a major-league career, as he doesn't miss enough bats (or induce enough grounders) to be a successful starter: it wouldn't be a shock to see him strike out between five and six batters per nine during his entire stint at Portland, and there are still two rungs left on that organizational ladder. We'll see, though, as he's still just 22, even if his repertoire suggests that relief is his eventual destination. Like Ramirez, Diaz is Rule 5 eligible in December, so the Sox might end up parting ways with him one way or another this year.