Nationals Prospect Weekly: Seaver King's Rochester rampage, Harmon's gem at Fredericksburg
By Marcus Bailey ·
Nationals Prospect Weekly covers the last 7 days of action for the Nationals farm system.
Seaver King's Triple-A Surge
Seaver King (AAA, SS, Rank: 3) had a remarkable week in Rochester. He went 11-for-31 with five home runs, a double, ten RBI, and six walks against eleven strikeouts across seven games, a line that looked more like a player announcing himself. His last-30-day numbers at the Triple-A level are something else entirely: a .382/.484/.750 slash over 91 plate appearances, eight home runs, seventeen RBI, and thirteen walks against twenty-three strikeouts. The power output is particularly striking given that his scouting profile grades the power tool at 45, a below-average projection that the results are currently making look conservative. His season line of .314/.394/.556 at Rochester across 236 plate appearances shows a hot week inside a genuinely excellent season.
The context matters because King's 2025 at Double-A was a sobering one: a .233/.287/.313 line in 357 plate appearances, a season that raised real questions about whether the hit tool could hold against upper-level sequencing. What 2026 looks like is a player who addressed the most glaring concern. His swing rate has held steady at 48.1 percent, right around the league average, while his walk totals have climbed sharply; he posted 22 free passes in 165 plate appearances at Double-A before the promotion and 21 in 236 at Triple-A. The contact rate of 75.4 percent has not been pristine, but the strikeout management and on-base ability are real. Combined across both levels, he is slashing .323/.407/.558 with 18 home runs and 14 steals in 401 plate appearances. He profiles as a second-division regular at shortstop, with some chance that number drifts higher if the power grade gets a revision after a full season of this. A big-league call is not a matter of whether; it is a matter of when the roster allows.
Nineteen Year Old Landon Harmon’s Breakout in Fredericksburg
Landon Harmon (A, RHP, Rank: 19) threw 7.1 innings against Low-A competition this past week, allowing three hits, one earned run, and two walks while punching out ten. The outing was the signature performance of a stretch that has been as good as any arm in the system over the last month. Over his last six outings at Fredericksburg, he carries a 1.00 ERA across 18 innings with 20 strikeouts, a 0.78 WHIP, and a whiff rate of 30.5 percent. For the season, the ERA sits at 1.39 across 32.1 innings with 31 strikeouts and a 0.84 WHIP, numbers that would be remarkable from any arm at this level and are especially so from a 19-year-old who was described at draft time as a developmental arm built around one plus offering.
That offering, a four-seam fastball that sits 95-96 mph and grades at 65, has been the carrying pitch as advertised, but what makes Harmon's results sustainable rather than fluky is the early development of his breaking ball mix. The 55-grade slider at 83 mph gives him a secondary weapon with genuine swing-and-miss capacity, and the curveball at 79 flashes average when he locates it down in the zone. His command grades at 50, and his 46.6 percent strike rate is workable for his age, though it will need to climb as he faces more advanced hitters who can punish early-count mistakes. The changeup at 45 remains the biggest question; without it, left-handed lineups can simply sit fastball-slider and eliminate the guesswork. None of that is an urgent problem right now, because nobody at this level is solving the heater. The projection is a number-four starter with a higher ceiling if the secondaries develop, and nothing about this stretch argues against that floor. I would take the over on the timeline, though; pitchers posting a sub-1.40 ERA at 19 move fast when healthy.
Quick Hits
Ethan Petry (AA, OF, Rank: 27) · drove in six runs on six hits in 19 plate appearances at Harrisburg, with three home runs and a double in the mix. The power is genuine and not up for debate: he has 22 home runs combined this season and a .529 slugging percentage at Double-A over his last 30 days. The friction is the contact side of the ledger. His swing rate has crept to 51.3 percent over the last month, and his contact rate sits at 63.3 percent over that same stretch, a combination that produces weeks like this one and weeks where the lineup card reads ugly. He is slashing .232/.305/.489 at Double-A on the year with 71 strikeouts in 210 plate appearances. The 60-grade raw power is loud; the 40-grade hit tool is keeping him from being a lock to stick at the corner outfield.
Devin Fitz-Gerald (AA, SS, Rank: 17) · went 6-for-19 at Harrisburg with a homer, a double, three walks, and a hit-by-pitch across the week. His season is a genuine split-level story: a .267/.373/.530 line with 12 home runs and 30 walks in 237 plate appearances at High-A before the promotion, followed by a .213/.291/.290 mark with 54 strikeouts in 203 plate appearances at Double-A. The last-30-day numbers at AA (.259/.365/.389) show some stabilization, and his contact rate of 77 percent over that stretch is the best it has been at this level. A switch-hitter with a 50 hit tool and 50 power grade, he projects as a second baseman with utility value; this week was a reminder that the bat from the better scouting-report version of Fitz-Gerald is still in there.
Cristhian Vaquero (A, OF, Rank: 35) · had five hits, two home runs, and four RBI across 22 plate appearances at Fredericksburg, with three walks and a pair of hit-by-pitches adding to the on-base total. His full-season numbers split dramatically by level: a .333/.424/.647 line with four home runs in 59 plate appearances at Low-A versus a .229/.309/.229 mark with no home runs in 56 plate appearances at High-A. The aggressive 57.9 percent swing rate and 63.6 percent contact rate are the reason the gaps exist; at Low-A, he can impose his tools, but the pitch recognition has not yet translated at the next level. The athleticism and speed grade at 60, the arm at 55, and the defensive profile in center is already the best part of his game. He is 21 with real center-field value, and the offensive ceiling is still a reasonable conversation if the contact rate climbs.
Kevin Bazzell (AA, C, Rank: 52) · was 3-for-10 with three RBI and a walk in limited appearances at Harrisburg. The more meaningful context is what he has done over the last month at High-A: a .349/.455/.651 slash across 56 plate appearances with three home runs, four doubles, and a contact rate of 82.1 percent. That power output is meaningful because he entered 2026 without a single professional home run in 329 plate appearances through 2025, so the seven he has posted this season represent a legitimate developmental step. A 55 hit tool with a contact-first approach and a 55 arm, he profiles as a bench catcher at best, but the bat is making a case for more looks at the upper levels.
Miguel Sime Jr. (A+, RHP, Rank: 20) · struck out six over 2.2 innings against Wilmington on four walks and two hits, a line that is more representative of the tension in his profile than the stat sheet makes clean. His last-30-day numbers at High-A are eye-popping: a 1.35 ERA across 20 innings with 34 strikeouts, a 51 percent whiff rate, and a contact rate that makes hitters look lost. He also issued 12 walks in that span, keeping his pitch-per-inning total inefficient at 19.7 for the season. The 70-grade fastball sitting 97-101 mph is the carrying tool, and the curveball gives him a second swing-and-miss shape; at 19, with that velocity and a 51.5 percent seasonal whiff rate, the ceiling is real. The 35-grade command is the wall between him and a rotation, and he has not found a consistent delivery yet to bring it up.
Jarlin Susana (AA, RHP, Rank: 5) · struck out eleven over 4.1 innings but was touched for four earned runs on four hits and a walk. His three-start sample at High-A this season reads 6.1 innings, 13 strikeouts, a 5.68 ERA, and a 42.6 percent whiff rate. The whiff number is what you would expect from a pitcher with a 65-grade fastball sitting 99-103 mph and a 65-grade slider; the run prevention has not followed because the command grades at 40 and the walks have not stopped coming. He threw 3 of every 10 pitches for balls in this start. The projection is a setup reliever or better if the strike throwing reaches league-average; the stuff to get there is already in place. Every Susana outing right now is a negotiation between the two.
Josh Hartle (AA, LHP, Rank: 32) · gave up two earned runs over four innings on four hits and a walk, with four strikeouts, a step down from his Harrisburg debut after the Cleveland trade. His last-30-day numbers at Double-A remain encouraging: a 2.11 ERA across 21.1 innings with 18 strikeouts, zero home runs allowed, and a 0.84 WHIP. His pitch-per-inning rate of 13.2 over that stretch rates as efficient. A four-pitch lefty with a 55-grade changeup as his best secondary weapon, he commands enough to project as a back-end starter. One uneven start after an encouraging debut does not change the read on him.
Riley Cornelio (AAA, RHP, Rank: 34) · went 3.2 innings with five hits, one earned run, a walk, and five strikeouts at Rochester. His Triple-A numbers over the last 30 days are genuinely strong: a 1.32 ERA across 13.2 innings with 20 strikeouts and a 33 percent whiff rate. His MLB line on the season is 5.40 ERA in 20 innings with 20 strikeouts and 20 walks, which tells you the stuff plays but the 45-grade command makes every big-league outing a tightrope. He remains a pitch-at-a-time arm; the slider is a real out pitch when it is on, and the fastball sits 94-97 as a reliever. The path forward is probably shorter stints where the two pitches can do the most damage before the walk rate catches up.