Kyle Harrison

Kyle Harrison

24-Year-Old PitcherSP
Boston Red Sox
2025 Fantasy Outlook
During his days in the minors when he became a top prospect, Harrison posted an ugly 12.3 percent walk rate but also a whopping 37.4 percent strikeout rate. Both of those numbers have come way down in the majors, with the lefty issuing walks at just a 7.8 percent clip but also fanning batters at a pedestrian 22.5 percent rate. Harrison's velocity also dipped in 2024 across the board and was down even more from August on when he posted a 7.76 ERA over six starts before he ended the season on the injured list with shoulder inflammation. Because it gets so much horizontal movement after he dropped his arm slot, Harrison's four-seamer still played well in spite of the lesser velocity, with the pitch earning a plus-seven Run Value. That said, the profile on the whole doesn't look as exciting as it did a year ago. Read Past Outlooks
RANKS
Rest of Season
From Preseason
#376
ADP
Signed a one-year, $760,000 contract with the Giants in March of 2025. Traded to the Red Sox in June of 2025.
Makes Boston debut
PBoston Red Sox
September 11, 2025
Harrison allowed three hits, hit a batter and struck out two over three scoreless relief innings in Wednesday's 5-4 loss to the Athletics.
Analysis
Harrison pitched the final three innings in a piggyback outing that was started by Payton Tolle (two innings). Harrison isn't fully built up after a series of stops and starts over the last couple of weeks that included an ankle injury. He could be a factor later in September, as he unlikely has the same innings limits of rookies Tolle and Connelly Early.
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Pitching Stats
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2025 MLB Game Log
2025
2024
2023
2025 MLB Game Log
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Scoring
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2024 MLB Game Log
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2023 MLB Game Log
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Pitching Appearances Breakdown
Average Pitch Count
49
Last 10 Games
49
Last 5 Games
72
How many pitches does Kyle Harrison generally throw?
 
1-10
 
11-20
 
21-30
 
31-40
 
41-50
 
51-60
 
61-70
 
71-80
 
81-90
 
91-100
 
101-110
 
111-120
 
121+
 
1-10
 
11-20
 
21-30
 
31-40
 
41-50
 
51-60
 
61-70
 
71-80
 
81-90
 
91-100
 
101-110
 
111-120
 
121+
 
1-10
 
11-20
 
21-30
 
31-40
 
41-50
 
51-60
 
61-70
 
71-80
 
81-90
 
91-100
 
101-110
 
111-120
 
121+
What part of the game does Kyle Harrison generally pitch?
 
 
 
1st
 
 
 
2nd
 
 
 
3rd
 
 
 
4th
 
 
 
5th
 
 
 
6th
 
 
 
7th
 
 
 
8th
 
 
 
9th
 
Extra
 
 
 
1st
 
 
 
2nd
 
 
 
3rd
 
 
 
4th
 
 
 
5th
 
 
 
6th
 
 
 
7th
 
 
 
8th
 
 
 
9th
 
Extra
 
 
 
1st
 
 
 
2nd
 
 
 
3rd
 
 
 
4th
 
 
 
5th
 
 
 
6th
 
 
 
7th
 
 
 
8th
 
 
 
9th
 
Extra
% Games Reaching Innings Threshold
% Games By Number of Innings Pitched
Left/Right Pitching Splits
Since 2023
 
 
-12%
BAA vs RHP
2025
 
 
-14%
BAA vs RHP
2024
 
 
-1%
BAA vs LHP
2023
 
 
-46%
BAA vs RHP
BAA Batters K BB H 2B 3B HR
Since 2023vs Left .275 185 39 11 46 6 2 9
Since 2023vs Right .243 607 141 51 132 30 1 21
2025vs Left .257 35 8 0 9 1 1 3
2025vs Right .221 78 19 9 15 5 0 1
2024vs Left .260 108 29 6 25 3 1 3
2024vs Right .263 424 89 36 100 22 0 15
2023vs Left .333 42 2 5 12 2 0 3
2023vs Right .179 105 33 6 17 3 1 5
More Splits View More Split Stats
Home/Away Pitching Splits
Since 2023
 
 
-9%
ERA at Home
2025
 
 
-76%
ERA on Road
2024
 
 
-17%
ERA at Home
2023
 
 
-58%
ERA at Home
ERA WHIP IP W L SV K/9 BB/9 HR/9
Since 2023Home 4.20 1.28 90.0 5 2 0 9.3 2.5 0.9
Since 2023Away 4.61 1.31 95.2 4 7 0 8.2 3.5 2.0
2025Home 9.45 1.80 6.2 0 0 0 6.8 1.4 1.4
2025Away 2.25 1.05 20.0 1 1 0 9.9 3.6 1.4
2024Home 4.14 1.29 63.0 4 2 0 9.3 2.4 0.9
2024Away 4.99 1.40 61.1 3 5 0 7.8 3.7 1.8
2023Home 2.66 1.08 20.1 1 0 0 10.2 3.1 0.9
2023Away 6.28 1.26 14.1 0 1 0 7.5 2.5 3.8
More Splits View More Split Stats
Stat Review
How does Kyle Harrison compare to other starting pitchers?
This section compares his stats with all starting pitcher seasons from the previous three seasons (minimum 120 innings)*. The bar represents the player's percentile rank. For example, if the bar is halfway across, then the player falls into the 50th percentile for that stat and it would be considered average.

* Exit Velocity, Barrels/BBE %, Balls Hit 95+ MPH %, and Spin Rate are benchmarked against 2019 data (min 120 IP). See here for more exit velocity/barrels stats plus an explanation of current limitations with that data set.
  • K/BB
    Strikeout to walk ratio.
  • K/9
    Average strikeouts per nine innings.
  • BB/9
    Average walks per nine innings.
  • HR/9
    Average home runs allowed per nine innings.
  • Fastball
    Average fastball velocity.
  • ERA
    Earned run average. The average earned runs allowed per nine innings.
  • WHIP
    Walks plus hits per inning pitched.
  • BABIP
    Batting average on balls in play. Measures how many balls in play against a pitcher go for hits.
  • GB/FB
    Groundball to flyball ratio. The higher the number, the more likely a pitcher is to induce groundballs.
  • Left On Base
    The percentage of base runners that a pitcher strands on base over the course of a season.
  • Exit Velocity
    The speed of the baseball as it comes off the bat, immediately after a batter makes contact.
  • Barrels/BBE
    The percentage of batted ball events resulting in a Barrel. A Barrel is a batted ball with similar exit velocity and launch angle to past ones that led to a minimum .500 batting average and 1.500 slugging percentage.
  • Spin Rate
    Spin Rate is the rate of spin on a baseball after it is released. It is measured in revolutions per minute (rpm).
  • Balls Hit 95+ MPH
    The percentage of batted balls hit that met or exceeded the 95 MPH threshold.
  • Swinging Strike
    The percentage of pitches that result in a swing and a miss.
K/BB
3.00
 
K/9
9.1
 
BB/9
3.0
 
HR/9
1.4
 
Fastball
95.1 mph
 
ERA
4.05
 
WHIP
1.24
 
BABIP
.293
 
GB/FB
1.00
 
Left On Base
76.6%
 
Exit Velocity
83.8 mph
 
Barrels/BBE
6.3%
 
Spin Rate
2247 rpm
 
Balls Hit 95+ MPH
25.8%
 
Swinging Strike
12.9%
 
Prospect Rankings History
Advanced Pitching Stats
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Defensive Stats
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Stats Vs Today's Lineup
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Recent RotoWire Articles Featuring Kyle Harrison See More
Recent RotoWire Articles Featuring Kyle Harrison See More
Past Fantasy Outlooks
2024
2023
2022
Harrison walked three or more batters in 11 of his 20 starts at Triple-A, where automated balls and strikes may have increased walk rates relative to when humans are calling the game. He walked at least one batter but no more than two batters in all seven of his big-league starts, which lends credence to the theory that he may have less of a control issue when the human element is involved. Harrison always missed bats at an elite clip in the minors, with strikeout rates north of 35 percent at every stop. However his propensity to walk batters has held him back at times. The gap between his walk rate at Triple-A (16.3 percent) and the big leagues (7.5 percent) is essentially the difference between a pitcher destined for relief and a pitcher who comfortably projects as a starter. The 6-foot-2 southpaw was the third-youngest pitcher to make five-plus starts in the majors (only Eury Perez and AJ Smith-Shawver were younger), so it's fair to expect further skill development in the coming years for Harrison, who won't turn 23 until August. He is a flyball pitcher (26.8 GB% in the big leagues), but he has a good home park for that approach, as Oracle Park has the third-lowest home run park factor, per Baseball Savant's 3-year rolling average. He should make the rotation out of spring training, but a hamstring injury limited him to 102.1 innings, so the Giants may cap him at around 150 innings in the regular season.
Harrison isn't a perfect pitching prospect, but he is as good as they come with regards to missing bats. The 21-year-old southpaw struck out 186 in 113 innings across 25 starts between High-A and Double-A, with the bulk of his work coming at Double-A. He has a standard three-pitch mix (fastball/slider/changeup) and can get whiffs on any of his pitches in any count if he executes. Harrison had an 11.2 BB% at Double-A, but he cut down on the walks as the summer went on, and most evaluators expect him to stick as a starting pitcher. He is a flyball pitcher (35.6 GB%, 11 HR allowed at Double-A), so assuming his command and control are never elite, he will likely fail to log ace-level ratios, even if he is one of the game's top strikeout arms. While Harrison is not on the 40-man roster, he is clearly the team's best young pitcher, so a 2023 MLB debut is in the cards if he earns it.
Harrison could be a frontline starter if the rest of his development goes smoothly. We shouldn't count on that happening, but his talent and upside were on full display last year. The 20-year-old southpaw struck out 157 over 98.2 innings at Low-A, but his 1.40 WHIP on the year was obviously a red flag. That said, he closed the year on a high note, logging an 0.97 ERA, 0.92 WHIP and 61:13 K:BB in 37 innings over his final eight starts. He can already touch 98 mph with his four-seam fastball, and his slider and changeup might be 70-grade offerings in time. Both offspeed pitches got whiffs at over a 40% clip last season. If his late-season control gains hold and he can stay healthy, Harrison should cruise through the minors and may eventually pitch atop the Giants' rotation.
More Fantasy News
Recalled to big leagues
PBoston Red Sox
September 10, 2025
The Red Sox recalled Harrison from Triple-A Worcester on Wednesday.
Analysis
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Could piggyback Tolle on Wednesday
PBoston Red Sox
September 10, 2025
The Red Sox plan to recall Harrison from Triple-A Worcester ahead of Wednesday's game against the Athletics in Sacramento, Chris Cotillo of MassLive.com reports.
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Could be added to roster Wednesday
PBoston Red Sox
September 9, 2025
Harrison is headed to Sacramento to join the Red Sox and could be recalled from Triple-A Worcester prior to Wednesday's game against the Athletics, Tommy Cassell of the Worcester Telegram & Gazette reports.
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Returns to action for Triple-A club
PBoston Red Sox
September 8, 2025
Harrison (ankle) made a one-inning start for Triple-A Worcester in the first game of a doubleheader Sunday, striking out two batters while allowing one earned run on two hits and one walk.
Analysis
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Managing ankle injury
PBoston Red Sox
Ankle
September 3, 2025
Triple-A Worcester manager Chad Tracy said Wednesday that Harrison is tending to an ankle injury, and the southpaw is without a clear timeline to resume pitching, Katie Morrison-O'Day of MassLive.com reports.
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Latest Fantasy Rumors
In mix for rotation spot
PSan Francisco Giants
May 22, 2025
Harrison is a candidate to enter San Francisco's rotation after Justin Verlander was placed on the injured list due to a pectoral injury Thursday, reports Alex Pavlovic of NBC Sports Bay Area.
Analysis
Harrison was called up in early May after missing out on the Opening Day rotation, and he's pitched well in four apperarances with a 3.38 ERA, 0.94 WHIP and 7:3 K:BB over 5.1 innings. The left-hander might be limited to about 50 pitches if called upon to start Saturday in Washington. Harrison had a 4.56 ERA over 24 starts in the majors last season, which was a decent showing for his first full season in the big leagues.
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