Fenway Farm Prospect Weekly: Castro's Monster Week at Worcester, Holobetz Deals at Triple-A
By James Collins ·
Fenway Farm Prospect Weekly covers the last 7 days of action for the Red Sox farm system.
Castro's Triple-A Power Binge Complicates a Simple Projection
Allan Castro (AAA, CF, Rank: 47) delivered the most productive week of his season at Worcester, going 8-for-22 with three home runs, three doubles, and 12 RBI across 22 plate appearances, including a career-high seven RBIs on September 19. The raw output is hard to dismiss. A switch-hitting outfielder with a 40 power grade and a bench projection just put up a power line that would look reasonable from a player two tiers above him on any prospect list. Over his last 30 days at Triple-A, he is slashing .282/.361/.577 with six home runs and 20 RBI in 83 plate appearances, with a contact rate that has climbed to 81 percent and a walk rate of 12.0 percent. That is a materially better version of Castro than what the season-long numbers describe.
The full-season picture deserves its own reading. Across 505 Triple-A plate appearances this year, Castro carries a .252/.325/.397 line with 15 home runs, which is a below-average contact rate and enough power to be interesting but not enough to clear the corner-outfield bar. His 45 hit tool and modest power grade frame the projection honestly: a bench outfielder whose value runs through switch-hitting, defensive versatility, and enough strike-zone awareness to hold a roster spot. The September numbers do not rewrite that, but they push the power question somewhere more interesting. Six home runs in 83 plate appearances over the last month is nearly a pace the full-season numbers could not sustain, and the walk rate spike to 12.0 percent suggests the plate approach has tightened as the power has arrived. A bench ceiling with real September power from both sides is at least more useful than a bench ceiling without it.
Holobetz Finds His Best Triple-A Form at the Right Time
John Holobetz (AAA, RHP, Rank: 19) went 4.1 innings last week, allowing no runs on two hits with two walks and eight strikeouts against 17 batters faced, generating 20 swinging misses on 66 pitches. It was the sharpest outing of his Triple-A run this season and fits a September stretch worth tracking. Over his last 30 days at Worcester, he carries a 1.31 ERA across 20.2 innings with 21 strikeouts and a contact rate that suggests the fastball-slider combination is genuinely uncomfortable when he is throwing strikes.
The season context matters here. Across 40.1 innings at Triple-A, Holobetz owns a 3.57 ERA with a 22.8 percent strikeout rate and a 6.4 percent walk rate, numbers that profile as fringe-average for a rotation candidate at that level. His fastball is a legitimate plus pitch with 17-plus inches of induced vertical break and armside run that plays well against right-handed hitters, and the 60 command grade has largely shown up in the form of a functional walk rate. The secondary concern, the changeup needing to become a more credible out-pitch, remains real: his combined strikeout rate across Double-A and Triple-A this season is 26.3 percent, workable but not dominant. The 20 whiffs on 66 pitches last week suggest the secondaries were sharper than they have been throughout August. A 24-year-old with a 60 command grade, a plus fastball, and a month of sub-2.00 ERA ball at Triple-A is a reasonable candidate for a September or spring look. Last week gave that case more structure than it had a month ago.
Quick Hits
Franklin Arias (AAA, SS, Rank: 1) · went 6-for-22 with a home run and seven RBI across 22 plate appearances last week, adding two walks and striking out three times. The weekly line is steady rather than spectacular, but the season body of work makes it land differently: he is slashing .323/.400/.557 combined across Double-A and Triple-A with 25 home runs and 91 RBI in 520 plate appearances. His 60 hit tool and 60 glove at shortstop have both shown up this year, and the 14.2 percent strikeout rate across the full season remains one of the better marks in the system. Over his last 30 days at Triple-A, he is hitting .375 with an 87.6 percent contact rate in 90 plate appearances, which is closer to the ceiling version of a 20-year-old shortstop than anything the prospect timeline would have predicted heading into the year.
Jedixson Paez (AAA, RHP, Rank: 15) · posted 5.2 innings with one earned run on three hits, no walks, and four strikeouts against 19 batters, generating 12 swinging misses on 71 pitches. The outing was efficient by his Triple-A standards, and the walk-free performance fits the 60 command grade that defines the profile. The larger picture is more complicated: his season MLB sample at both Boston and Chicago produced an 18.00-plus ERA across six combined innings, and his Triple-A numbers this year, a 2.08 ERA across 21.2 innings in five starts, have looked excellent in small doses before the big-league exposure. The changeup at 55 and the slider at 50 give him real weapons, but the 92-94 mph fastball graded at 45 means precision is non-negotiable. Over his last 30 days at Triple-A, he carries a 5.09 ERA across 17.2 innings with a 26.4 percent strikeout rate, which is useful but points to some homer vulnerability. The command profile gives him a floor; what the ceiling looks like against major-league lineups is still an open question after this season's evidence.
Gage Ziehl (AAA, RHP, Rank: 29) · turned in 5.2 innings last week with one earned run, one walk, four hits, and three strikeouts against 22 batters, generating just five swinging misses on 76 pitches. The strikeout rate over his last 30 days at Triple-A sits at 17.0 percent across 26 innings, down from the 27.1 percent he posted in 81 Double-A innings earlier in the season. The sweeper-cutter pairing that worked as his bat-missing engine at Portland has not generated the same swing-and-miss results at the higher level, and the 40-grade fastball is predictably more exposed as hitters get better. His season ERA at Triple-A is 4.17, and the last-30-day ERA of 4.50 does not represent a sustained step backward so much as a reflection of what a plus command grade and a 40-grade heater can do against Triple-A lineups when the sweeper is not at its sharpest. The floor here is real because of the strike-throwing, but last week was a reminder that the ceiling has a cap.