Red Sox prospects daily: When will Boston promote Rusney Castillo?

Triple-A Pawtucket: Rusney Castillo, RF

Rusney Castillo is currently on the minor-league disabled list with a shoulder injury, but there is no structural damage and the Red Sox expect him back in game action within the next nine days or so. All Castillo has done since coming to the United States from Cuba is mash, so if he picks up where he left off, the questions about when he'll be in the majors again are going to come more often, and much louder. You can assume that'll be even more the case if starting right fielder Shane Victorino still isn't hitting by the time Castillo is ready to go.

So, when is the moment where Castillo ends up back in Boston? Last year provides a little bit of a hint: the Red Sox demoted Daniel Nava to Triple-A Pawtucket in late-April, with his last Boston game coming on April 21 after batting .149/.240/.269 to begin the year. There are some key differences between Victorino and Nava -- Shanf is a defensive wonder in right, he's being paid $13 million, and isn't going to be optioned to Triple-A to make room for a rookie. However, Nava was pushed aside at a time the Sox still felt they were contenders, and this occurred without anyone like Rusney there to take his place.

The Sox were still toying with Grady Sizemore in the outfield at that point, and Jonny Gomes got the start in left on April 25, Nava's first day back in Pawtucket. Sure, Sizemore had some promise, but Castillo is a plus defender who might just have the bat to get the Boston lineup going in 2015. It wouldn't be shocking if the Sox gave up on the idea of keeping Allen Craig by mid-May if Victorino still hasn't gotten hot, in order to make Victorino the fourth outfielder and their go-to defensive backup.

Of course, Victorino has to be healthy for that to happen, and he's missed time recently dealing with his ribs and the kind of rest necessary for someone who recently underwent back surgery. Victorino shouldn't lose his job outright to Castillo because his aggressive play can sometimes hurt him -- hell, Castillo landed on the DL because of a diving catch -- but if he continues to look like a problem in the lineup, Boston can only keep Rusney in Triple-A for so long.

Triple-A Pawtucket: Heath Hembree, RHP

If the Red Sox make upgrades to their bullpen during 2015, a few of them could likely just be called up from Pawtucket. Hembree is one such arm, a 26-year-old righty on the 40-man roster whose presence helped make Alex Wilson expendable this offseason -- Wilson was mostly an up-and-down reliever for Boston, a pitcher who they used when they had to, but one who never fully carved out a permanent presence on the Sox. Hembree could have a brighter future, and he's younger to boot, so sticking with him and dealing Wilson with Yoenis Cespedes to get Rick Porcello to the Sox made all kinds of sense.

Hembree was originally acquired from the Giants in the last July's Jake Peavy deal along with starting pitching prospect Edwin Escobar, and while he's absolutely a reliever, he could be a good one. He's pitched in five games to this point in 2015, striking out 10 batters in seven innings without allowing a run thanks to just four baserunners. That's picking up right where he left off in 2014, when he gave up just two runs over 6-2/3 innings, though, this time he seems to know where the ball is going when it comes out of his hand. It helps that he's not pitching in the hitter-friendly Pacific Coast League, either: developing pitchers and pitches is a lot simpler when half the ballparks aren't tiny versions of Coors Field.

Hembree has thrown just 17 innings in the majors in his career, but they went well enough, with over nine strikeout per nine and a 2.6 strikeout-to-walk ratio to go along with his 2.55 ERA. He's not going to keep that kind of ERA forever -- if he could, he'd be in the majors right now -- but he should be a useful arm for bridging the gap from the starters to the back-end of the Boston bullpen. As early returns this April have suggested, someone like that could end up with plenty to do this summer.

High-A Salem: Trey Ball, LHP

It's early, so you can ignore Trey Ball's 5.06 ERA over three starts. He's thrown just 16 innings to this point, so it's tough to make dramatic statements about whether a still-raw pitcher the Sox promoted up a level is in trouble or not. At this point, we're still in watch-and-see mode. What we see right now is that he has given up four homers -- two in his last start -- and but has been doing a better job of separating his walk and strikeout totals to this point. What can we take from that? Well, not a whole lot.

Ball is still learning how to pitch. Last year he learned that professional baseball hitters are not high school ones. This year, he has to figure out not just how to throw strikes, but how to throw quality strikes. Once he starts to figure out that he can't leave a pitch in a certain place, or that he can rack up more strikeout by painting the black or by using his secondaries low, away, or both, you should start to see the strikeouts tick up and the homers decline. It's a process, though, one that's going to include starts like his last one. Pitchers can't learn where not to throw the ball until they are given a reason to learn, much like young hitters need to find out which pitches they can do something with and which they should lay off.

Remember, too, that while this is considered Ball's age-21 season, he won't actually turn 21 until June 27 -- three days before the seasonal age cutoff. Had he been born four days later -- just four! -- you'd see a lot more patience for someone in his age-20 season. Try to keep that in mind as you see his struggles, and remember that, even with them, he's in High-A ball two years after being drafted out of high school.

Low-A Greenville: Jalen Beeks, LHP

Jalen Beeks was Boston's 12th-round pick in the 2014 draft, but he probably would have gone earlier than that if not for elbow issues that hurt his draft stock. There is always the concern those come up again, but for now, he's a pitcher the Sox got later and for less money than they would have were they not attached to him. It's a gamble, but given the minimal investment, one worth taking.

The short lefty -- Beeks is just 5-foot-11 -- projects as a possible big-league reliever, according to Sox Prospects. He has touched 95 miles per hour in the past but works a couple ticks lower, but from a lefty out of the bullpen, that's plenty of gas. He hasn't been missing many bats with it yet, but it's early, too, and as least he hasn't been missing the strike zone: Beeks has a 5.5 strikeout-to-walk ratio in his first 14-2/3 innings. If you think that's a whole lot of innings for a reliever by this point, you're right: the Sox have Beeks starting for now, in order to help him flesh out his repertoire a bit.

It might never get that reliable third pitch, but if all Beeks ends up as is a lefty who can hit the mid-90s on occasion, and do so accurately, then he'll get his chances.