That time of year. I do respect the paywall, so just put out the relevant extracts:

http://insider.espn.go.com/mlb/story...0prospects2015

http://insider.espn.go.com/mlb/story...-prospects-mlb

http://insider.espn.go.com/mlb/story...kings-2015-mlb

Red Sox #5 system in the league

The Red Sox lost four top-10 prospects to promotions last year, yet they remain a top-5 system, thanks to big moves forward by Blake Swihart, Manuel Margot and Rafael Devers, the latter of whom will play all of 2015 at age 18, and the midseason trade that netted them lefty Eduardo Rodriguez, now their No. 2-ranked pitching prospect.
Guys in the Top 100

10. Blake Swihart (#56 last year)

In an era when no one seems to have any catching, the Red Sox are fortunate enough to have two young backstops close to major league-ready in defensive specialist Christian Vazquez, now their primary catcher for 2015, and top prospect Swihart, a supreme athlete who is nearly as good a defender as Vazquez but with All-Star upside with the bat.

Swihart is a switch-hitter who was a part-time catcher in high school but has taken to the position incredibly well in pro ball, improving rapidly in every aspect of the game, to the point where he's now a plus or better receiver with a 65 to 70 arm (nailing 46 percent of would-be base stealers in 2014). He's built like a middle infielder or center fielder, with a lithe, athletic body, and runs better than most backstops do. At the plate, his hand-eye coordination is outstanding and has helped carry him as his pitch recognition and power have developed over the past three seasons. His right-handed swing is better and still produces more power, but he's improving from the left side and has the loft to hit 10-15 homers against right-handers.

The Red Sox have long raved about Swihart's work ethic and aptitude, both critical in developing a true two-way catcher given the mental and physical demands of the job.
20. Henry Owens (#42 last year)

Owens continues to rack up huge strikeout numbers (fourth in the minors in 2014) despite the lack of a big fastball, thanks to one of the minors' best changeups and a ton of deception that leaves hitters guessing until it's almost too late to adjust to whatever he's thrown. He still has some projection remaining, and some work to do on the breaking ball, putting him perhaps a half-year away from the major league rotation once there's a spot for him.

Owens will pitch at 90-94 mph, even sitting in the lower end of that range but getting a little more velocity once he needs it. The changeup is his money pitch, as his arm speed is indistinguishable between that and the fastball and he knows how and when to use it, but in the early part of 2014, hitters started to adjust to the fact that he was mostly fastball/changeup, forcing him to work on the curveball more to change eye levels. That pitch, in the mid- to upper 60s in high school, is now 72-76 and at least fringe-average with a change to be above-average to plus in time; the spin is there, but the rotation needs to keep getting tighter, though the fact that he can throw it for strikes is a huge help already. He'll probably pitch with an average fastball or just slightly better, but a 70 change and a 55 curveball with good command and an advanced feel for setting up hitters adds up to a well above-average major league starter.
29. Eduardo Rodriguez (#43 last year)

The Red Sox stole Rodriguez from the Orioles in a deadline deal for reliever Andrew Miller, who is a great pitcher to be sure, but not enough to make me willing to give up six years of Rodriguez, who has the elements to be a No. 1 starter with a few developmental hurdles ahead of him. Rodriguez is up to 97 mph with his fastball and will sit between 93 and 95, with a plus changeup, quick arm and athletic delivery. He seemed to gain confidence after the trade, throwing harder with better strikes once he went to Boston.

Fastball command is one real issue, although the Red Sox were pleased with how well he could work side to side with the pitch, and the slider is another, as I've seen it anywhere from a 50 grade to a 40. To be a No. 1 or No. 2, he needs to have that as a solid average or better pitch. He turns 22 in April, young enough for these two problem areas to improve, and the change of scenery seems to have agreed with him. He's not major league-ready, and is not likely to be so this year, but he should be in Boston's rotation in 2016.
55. Rafael Devers (Unranked last year)

Devers signed in July 2013 for $1.5 million, and the Red Sox, believing his approach was mature enough to handle it, pushed him to the Gulf Coast League midway through this summer. Despite his youth -- he was the third-youngest regular in the GCL -- and his late arrival, he finished tied for eighth the league in homers, and was also 12th in slugging percentage. Everything he does at the plate is easy; his wrists are extremely strong and quick, so he can backspin the ball all over the field, crush it to right-center or drive it out to the left-field wall, and he adjusts very well to changing speeds. He's very capable at third base despite his broad frame, with quick feet and more agility than you'd expect from his build, although he split time at the position last year with first-round pick Michael Chavis.

Devers turned 18 in October and is probably three years away from the majors in an optimistic scenario, but he has All-Star upside, with the bat speed and strength to hit 30 homers and still post high batting averages while staying at third base.
70. Manuel Margot (Listed last year as org sleeper)

Margot isn't flashy or explosive like system mate Rafael Devers, but he has been very steady and performed very well last year in two full-season leagues, all before his 20th birthday. He's an above-average defender in center field with good reads, and he has a simple, selective approach at the plate that has allowed him to succeed even when facing older and more experienced competition. His swing has good rotation but produces only doubles power; he might peak at 12 to 15 homers but could be a 35-plus doubles guy because he's able to go the other way so effectively.

He's currently a plus runner and should be a stolen-base threat in the majors as long as he doesn't get too big, although that same issue would be the only reason he'd move out of center field. It's a strong leadoff profile with the chance for high OBPs and 30-odd steals a year along with grade-60 defense, as long as he continues to work on his patience and can maintain his conditioning to stay in center.