Yilber Diaz

24-Year-Old PitcherRP
Arizona Diamondbacks AAA
2025 Fantasy Outlook
Coming into 2024, Diaz was known to have some of the best stuff in Arizona's farm system, but his shaky control led many to project a future relief role. Diaz's 8.5 percent walk rate in 50.1 innings at Triple-A was easily his best mark to date, which is impressive considering the ball and strike challenge system at Triple-A and the fact it was Diaz's first exposure to that level of competition. He logged 104.1 innings in the minors split between Double-A and Triple-A and did two stints with the big-league club, where he logged 28.1 innings while splitting time between the rotation and the bullpen. His 96.1 mph average fastball ranked in the 81st percentile just based on velocity, but the pitch played down (.388 xwOBA) due to average ride, poor extension and the shaky command one would expect from a rookie. His slider, meanwhile, had a 36.5 percent whiff rate and was his primary put-away pitch. Diaz's knuckle curveball is an OK third pitch, but he was much better against same-handed batters (9.7 K-BB%) than against lefties (1.8 K-BB%), which is not surprising given how much he leans on his fastball and slider. The Diamondbacks are a good team with a good defense, but Diaz is probably no higher than eighth on the organizational depth chart, so he will likely spend a decent amount of time back in the Triple-A rotation. Read Past Outlooks
RANKS
Rest of Season
From Preseason
#368
ADP
$Signed a one-year contract with the Diamondbacks in July of 2024.
Headed back to Triple-A
PArizona Diamondbacks  AAA
April 27, 2025
The Diamondbacks optioned Diaz to Triple-A Reno on Sunday.
ANALYSIS
Diaz was called up from Triple-A on Friday and made his 2025 debut against Atlanta, but he was roughed up for three runs on four hits and three walks over three innings while striking out one batter. Arizona selected Scott McGough's contract from Reno in a corresponding move.
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Pitching Stats
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2025
2024
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Pitching Appearances Breakdown
Average Pitch Count
60
Last 10 Games
60
Last 5 Games
60
How many pitches does Yilber Diaz 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 Yilber Diaz 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
 
 
-16%
BAA vs LHP
2025
 
 
-76%
BAA vs LHP
2024
 
 
-2%
BAA vs LHP
2023
No Stats
BAA Batters K BB H 2B 3B HR
Since 2023vs Left .241 64 10 9 13 4 1 0
Since 2023vs Right .286 70 10 6 18 3 1 3
2025vs Left .143 7 0 0 1 1 0 0
2025vs Right .600 8 1 3 3 1 0 0
2024vs Left .255 57 10 9 12 3 1 0
2024vs Right .259 62 9 3 15 2 1 3
2023vs Left 0 0 0 0 0 0 0 0
2023vs Right 0 0 0 0 0 0 0 0
Home/Away Pitching Splits
Since 2023
 
 
-80%
ERA at Home
2025
 
 
-100%
ERA on Road
2024
 
 
-86%
ERA at Home
2023
No Stats
ERA WHIP IP W L SV K/9 BB/9 HR/9
Since 2023Home 2.70 1.24 26.2 1 0 0 6.1 4.4 0.7
Since 2023Away 13.50 2.79 4.2 0 1 0 3.9 3.9 1.9
2025Home 9.00 2.33 3.0 0 0 0 3.0 9.0 0.0
2025Away 0 0 0 0 0 0 0 0 0
2024Home 1.90 1.10 23.2 1 0 0 6.5 3.8 0.8
2024Away 13.50 2.79 4.2 0 1 0 3.9 3.9 1.9
2023Home 0 0 0 0 0 0 0 0 0
2023Away 0 0 0 0 0 0 0 0 0
Minor League Left/Right Pitching Splits (AAA)
Since 2023
 
 
-13%
BAA vs LHP
2025
 
 
-11%
BAA vs RHP
2024
 
 
-25%
BAA vs LHP
2023
No Stats
BAA Batters K BB H 2B 3B HR
Since 2023vs Left .237 132 35 15 27 7 1 2
Since 2023vs Right .273 181 47 18 44 9 0 5
2025vs Left .306 46 7 8 11 2 0 0
2025vs Right .271 56 12 7 13 4 0 3
2024vs Left .205 86 28 7 16 5 1 2
2024vs Right .274 125 35 11 31 5 0 2
2023vs Left 0 0 0 0 0 0 0 0
2023vs Right 0 0 0 0 0 0 0 0
Stat Review
How does Yilber Diaz compare to other relievers?
This section compares his stats with all relief pitcher seasons from the previous three seasons (minimum 30 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 30 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
0.33
 
K/9
3.0
 
BB/9
9.0
 
HR/9
0.0
 
Fastball
94.6 mph
 
ERA
9.00
 
WHIP
2.33
 
BABIP
.349
 
GB/FB
1.33
 
Left On Base
57.1%
 
Exit Velocity
0.0 mph
 
Barrels/BBE
0.0%
 
Spin Rate
0 rpm
 
Balls Hit 95+ MPH
0.0%
 
Swinging Strike
3.3%
 
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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More Fantasy News
Called up Friday
PArizona Diamondbacks  AAA
April 25, 2025
The Diamondbacks recalled Diaz from Triple-A Reno on Friday.
ANALYSIS
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Sent to Triple-A
PArizona Diamondbacks  AAA
March 10, 2025
The Diamondbacks optioned Diaz to Triple-A Reno on Monday, Alex Weiner of ArizonaSports.com reports.
ANALYSIS
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Sent back to Reno
PArizona Diamondbacks  AAA
September 26, 2024
The Diamondbacks optioned Diaz to Triple-A Reno on Thursday.
ANALYSIS
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Recalled from Triple-A
PArizona Diamondbacks  AAA
September 12, 2024
The Diamondbacks recalled Diaz from Triple-A Reno on Thursday, Jesse Friedman of GoPHNX.com reports.
ANALYSIS
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Returns from minor-league IL
PArizona Diamondbacks  AAA
August 19, 2024
Diaz (finger) was reinstated from Triple-A Reno's 7-day injured list Thursday and struck out six while allowing three runs on four hits and two walks over five innings in his return to the club's rotation.
ANALYSIS
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