The Rule 5 draft happens each year as the conclusion of the winter meetings, and this time around, the Red Sox lost a couple of relievers they didn't protect on their 40-man roster a month prior. Those pitchers -- Ryan Pressly and Josh Fields -- have been participating in spring training with their new clubs, as they need to decide if it's worth using the major-league roster spot on them or if they should be returned. Given the situations for the pitchers and teams, however, it seems as if there is little chance of Boston reacquiring either arm.
Pressly has thrown 10 innings this spring, and while he's struck out just three batters, he's also only walked three while allowing five hits and a single run. It's spring training stats for a reliever, so don't get too excited in either direction, but Pressly has also done very well since his switch to the bullpen. The Red Sox promoted him to Double-A last summer and converted him to relief, which saw him drop his ERA from 6.28 to 2.93 in 27 innings. He followed up that performance with a great run in the Arizona Fall League, punching out 18 batters in 14 innings while allowing a single walk. His ERA was 3.86, but this is the AFL we're talking about: it's a hitters' league, and anything that doesn't make you cringe is worth noticing, especially with that strikeout-to-walk ratio.
This doesn't mean the Red Sox lost a great big-league reliever, but the Twins are in a position to try him out in the role in the majors, and will likely be able to stick with him in the long run in that role given his initial conversion, AFL stint, and good enough spring. If not, Boston could get him back and keep him off of the 40-man once again, but that's unlikely to happen at this point unless Pressly is a colossal mess in the majors and the Twins desperately need the roster spot.
As for Fields, he hasn't done nearly as well this spring on the surface, with three runs allowed in five innings. However, even without the whole "five innings in spring training" thing, he's struck out more than he's walked and is inducing outs on the ground. The Astros, even more so than the Twins, can afford to stick with Fields on their roster all season long in the majors unless he's outright horrific. And, if that's the case, then there's not much reason to be excited about getting him back in Boston, given he's already 27 years old.