{"id":577746,"date":"2026-02-17T16:14:15","date_gmt":"2026-02-17T16:14:15","guid":{"rendered":"https:\/\/www.rawchili.com\/mlb\/577746\/"},"modified":"2026-02-17T16:14:15","modified_gmt":"2026-02-17T16:14:15","slug":"colorado-rockies-prospects-no-8-sean-sullivan","status":"publish","type":"post","link":"https:\/\/www.rawchili.com\/mlb\/577746\/","title":{"rendered":"Colorado Rockies prospects: No. 8, Sean Sullivan"},"content":{"rendered":"

8. Sean Sullivan<\/a> (398 points, 19 ballots)<\/p>\n

Despite a professional career that has been marred by injuries and an accompanying loss in velocity, Sullivan keeps getting upper-minors hitters out \u2014 a lot of them via strikeout. The 6\u20194\u201d, 23-year-old lefty pitcher was dominant at Wake Forest, pitching 69 2\/3 innings with with a 2.45 ERA, 0.92 WHIP (fourth-best in Division 1), a 14.3 K\/9 rate (second-best), and a 2.7 BB\/9 rate as the Demon Deacons made it all the way to the College World Series semi-finals.<\/p>\n

Future Value: 40+, back-end starter<\/p>\n

Contract Status: 2023 Second Round, Wake Forest University, Rule 5 Eligible After 2026, three options remaining<\/p>\n

Sullivan (whose delivery reminded the Rockies of Kyle Freeland) rode those numbers to a $1.7 million bonus from the Rockies that was about $187k below slot. The 6\u20194\u201d southpaw relies mostly on his fastball which, despite velocity that is usually only in the 87-91 MPH range, is an effective pitch due to a low, wide release angle that gives it great carry up in the zone. He pairs that offering with a slider and change-up, but the fastball is the main separator.<\/p>\n

In High-A Spokane in 2024, Sullivan threw 83 1\u20443 innings in 14 starts with a 2.16 ERA (2.79 xFIP), 0.84 WHIP, 10.9 K\/9 rate, and a minuscule 0.9 BB\/9 rate (including a nine-inning complete game). That was enough in the High-A Northwest League to receive their Pitcher of the Year award<\/a> even though the Rockies promoted Sullivan in August to Double-A Hartford, where Sullivan was 3.5 years younger than league average.<\/p>\n

Sullivan maintained his excellent run prevention against Eastern League hitters, throwing 32 innings across seven starts with a 1.97 ERA. Sullivan wasn\u2019t nearly as dominant, striking out only less than a batter per inning (6.8 K\/9) and walking a few more (2.0 BB\/9) en route to a 4.37 xFIP. Still, a 1.09 WHIP with that ERA was a strong achievement for one of the younger pitchers in Double-A (the batter was older than him 80% of the time).<\/p>\n

Recovery related to an offseason surgery for a hip injury delayed Sullivan\u2019s 2025 debut back at Hartford (where he was still 2.7 years younger than average) to mid-May (after a scoreless rehab outing for both the ACL team and Low-A Fresno). In 18 starts and 97 1\/3 innings with Hartford, Sullivan posted a 3.14 ERA (3.39 xFIP), 1.09 WHIP, 9.0 K\/9 rate, and 2.2 BB\/9 rate.<\/p>\n

Those numbers were trending better before Sullivan went to the IL briefly in August and was hit hard in his final four starts of the year (allowing 13 earned runs in 16 2\/3 innings) after returning. Seven of Sullivan\u2019s Double-A starts were Quality Starts, while Sullivan allowed just a .611 OPS to opposing hitters (with basically no platoon splits). That was enough for Sullivan to get an invite to Major League spring training this year<\/a> by the Rockies.<\/p>\n

Here\u2019s some video of Sullivan striking out a bunch of dudes in 2025, many of them swinging:<\/p>\n

Keith Law of the Athletic ranked Sullivan 7th in the system<\/a> earlier this month:<\/p>\n

Sullivan had hip labrum surgery after the 2024 season and started the 2025 season about six weeks late, pitching well enough in Double A even though his fastball wasn\u2019t 100 percent to where it was beforehand. Sullivan has never thrown hard; at his best, his fastball is 89-92 but the pitch misses bats thanks to a very low release point, over seven feet of extension (OK, that hurts my hip just thinking about it) and excellent ride on the pitch. He\u2019s got an above-average slider with good tilt and an average changeup, going right after hitters like he\u2019s throwing 98. Sullivan had a lot of outings last year where he was sitting in the upper 80s, and that won\u2019t play, but if he\u2019s even just 89-92 again, I think he\u2019ll be a back-end starter. Side note: I really like watching this guy pitch.<\/p>\n

John Trupin of Baseball Prospectus ranked Sullivan 10th<\/a> last January with a 50 OFP:<\/p>\n

The 6-foot-4 southpaw leans heavily to his arm side as he deals, releasing the ball beyond the mid-point of the left-handed batter\u2019s box at a low 3\/4ths angle that is more accurately a high sidearm. The VAA created is subsequently disorienting for hitters, and indeed batters were flummoxed by Sullivan all year, swinging under his four-seam despite its meager velocity. That set up Sullivan\u2019s sweeping slider, a devastating pitch which plays up off Sullivan\u2019s angle and his plus command. Though his changeup is more sparingly utilized, the fastball-slider combination is effective enough to efficiently carve through lineups before they can get too comfortable. The margin for error is so thin for a pitcher with such little velo, but Sullivan\u2019s results continue to outpace the radar gun. His heater and slider are effective enough that a bullpen role will be quite reasonable if he does ultimately hit a wall against big-league bats. He\u2019s close enough to make Albuquerque this year, and polished enough to get a crack in Denver if his schtick keeps playing.<\/p>\n

Many command and control arms with bat-missing stuff in the low minors can\u2019t keep it up in the bigs. Sullivan already saw his swings and misses dip at Double-A, but he continued getting awkward swings and weak contact. This either works or it doesn\u2019t, but Sullivan seems unlikely to change it up significantly.<\/p>\n

MLB Pipeline slots Sullivan 12th in the system as a 45 FV player<\/a> thanks to a 60 control grade:<\/p>\n

Sullivan uses a lower slot to come at hitters with a kind of upshoot fastball, getting huge carry up in the zone. Even though it only averaged around 88 mph in 2024, the lefty threw it a lot and got decent swing-and-miss on the pitch thanks to that life and his outstanding command of the pitch. There could be a little more velocity in the tank now that he\u2019s had a hip labrum issue fixed, so he might be able to get to 93-94 mph more moving forward. His upper-70s changeup is his best pitch, one that has terrific movement and misses bats in and out of the zone. His sweeping slider can be effective, but he doesn\u2019t locate it as well as his other two offerings.<\/p>\n

The Rockies will be sure to bring Sullivan along slowly and manage his workload as he\u2019s coming back from the hip issue, but he\u2019s already defied expectations thanks to confidence in his pitch usage, his unusual mechanics and his extreme strike-throwing ways. He\u2019ll be at the upper levels continuing to show that his unusual profile just might work in a big league rotation.<\/p>\n

Eric Longenhagen of FanGraphs is less of a believer due to the low fastball velocity, grading Sullivan as a 40 FV player<\/a> (with a multi-inning relief role), 19th in the org, albeit with a 70 future command grade:<\/p>\n

Sullivan is an ultra-deceptive cross-bodied lefty with 20-grade velocity. He\u2019s done well in the mid-minors despite sitting 87 mph because of a mix of deception, command, and quality secondary stuff. Sullivan\u2019s stride direction takes him toward the first base line at an extreme angle, and this, in concert with his low three-quarters slot, takes hitters a few looks to get comfortable with. Sullivan\u2019s fastball averaged 90 mph in 2023 and 87 mph in 2024, but he still managed a 2.11 ERA, 125 strikeouts and just 15 walks across 115.1 innings, good for a microscopic 3.4% walk rate. In college, Sullivan\u2019s repertoire was fastball-heavy in the extreme at about 75% usage. His usage is still really high (67% in 2024), but he\u2019s been branching out in pro ball and his changeup generated huge rates of chase and miss last year. His slider plays by virtue of Sullivan\u2019s odd release. It\u2019s fair to be skeptical that this will actually work in a starting pitcher capacity \u2014 asking a guy who sits 87 to navigate a big league lineup three times feels like too much \u2014 but in short relief bursts where hitters have no time to adjust to Sullivan\u2019s funk, he should be fine.<\/p>\n

Between Chase Dollander, Sullivan, and Cole Carrigg, Colorado\u2019s first three picks of the 2023 draft all look like hits so far \u2014 not to mention Kyle Karros in the fifth round and Seth Halvorsen in the seventh. Sullivan\u2019s college dominance with his fastball has carried over to the minor leagues in a big way, even up to Double-A. The decreased fastball velocity is obviously a concern, though the development of a decent changeup and slider to pair with the fastball are certainly helpful.<\/p>\n

The Rockies could use Sullivan in the Major Leagues as soon as this year so long as his health cooperates and his fastball continues to bedevil advanced hitters (I suspect he\u2019ll mostly be at Triple-A Albuquerque). I ranked Sullivan 11th on my list as a 40+ FV player because of the pedigree, statistical dominance, and because I want the Rockies to continue to think more out of the box with their pitching draftees.<\/p>\n

Please keep in mind our Purple Row Community Guidelines<\/a> when you\u2019re commenting. Thanks!
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