Mason Barnett
SP · R/R · age 25.9 · ATHOCTOBER OK
OPTIONED
0+034
0+108 / 0+108
3 (using one in 2026)
1 of 5
PRE-ARBITRATION / AUTO-RENEWAL
Trade (KCR) Jul'24
0 / 0
none listed
Next 90 days, by the model
62%
17%
18%
2%
1%
Pushing the cut risk up: this season's WAR (-0.67) raises it, roster status (3) raises it, share of appearances as a starter (1) lowers it.
Context the model does not weigh: ZiPS projects 1.2 WAR, -0.7 WAR this season; 12 SP on the 40-man.
Trained on every 40-man roster snapshot since 2011 and what happened in the following 90 days; it sees roster status, options, service, history and last season's line, not this season's performance or the club's intentions. How well it does.
Is there a job for him next year?
ATH returns 12 SP on the 40-man once nobody leaves; about 8 SP jobs survive a normal winter. By his own recent record he ranks 11th among the returners (-0.8 WAR against a bar of 0.0), which the calibrated model turns into 47% kept through the tender deadline. Ranked by ZiPS and Steamer instead, which credit his longer track record, he is 7th (0.7 WAR, bar 0.5), worth 77% kept on the same model.
| By recent record: returning SP | Proj. WAR |
|---|---|
| 1. Luis Severino | 1.7 |
| 2. Gage Jump | 1.7 |
| 3. J.T. Ginn | 1.4 |
| 4. Jacob Lopez | 1.2 |
| 5. Jackson Perkins | 0.6 |
| 6. Jeffrey Springs | 0.5 |
| 7. Braden Nett | 0.0 |
| 8. Henry Baezlast job | 0.0 |
| 9. Joey Estes | -0.1 |
| 10. Gunnar Hoglund | -0.5 |
| 11. Mason Barnett | -0.8 |
| 12. Kade Morris | -0.9 |
| By ZiPS / Steamer: returning SP | Proj. WAR |
|---|---|
| 1. Jeffrey Springs | 1.9 |
| 2. Luis Severino | 1.8 |
| 3. Jacob Lopez | 1.5 |
| 4. J.T. Ginn | 1.1 |
| 5. Gage Jump | 1.1 |
| 6. Jackson Perkins | 0.7 |
| 7. Mason Barnett | 0.7 |
| 8. Kade Morrislast job | 0.5 |
| 9. Henry Baez | 0.5 |
| 10. Braden Nett | 0.3 |
| 11. Joey Estes | 0.3 |
| 12. Gunnar Hoglund | 0.1 |
Departing free agents are excluded; players on club, mutual or player options are counted as returning. The kept probability is calibrated on every September since 2012 using the recent-record projection; the ZiPS/Steamer reading uses the same model with a different ranking, so treat it as a second opinion rather than a calibrated number. Salary enters once arbitration projections publish in October.
October: Post-season eligible
On the 40-man before noon ET Sep 1. He stays eligible as long as he remains on the 40-man or 60-day IL through the post-season; an outright after the cutoff would end automatic eligibility.
The post-season eligibility list is fixed at noon ET on September 1: everyone on the 40-man, the 60-day IL or the military list at that moment, who then stays there without interruption. Attachment 25 (Major League Rule 40)
What happens if the club…
- option him to the minors
- Yes, 3 option years left. 1 of the five optional assignments for 2026 remain. A 2026 option year is already used (100 days), so further trips this season cost nothing extra. Once down he must stay 15 days unless he replaces an injured or traded player.
- Option years and the 20-day rule · Five optional assignments per season · Minimum stay on option
- designate him for assignment (or put him on outright waivers)
- The club has 7 days to trade him, pass him through outright waivers, or release him; he is paid at the major-league rate and keeps accruing service in the meantime. On outright waivers any club can claim him for $50,000, worst record first, and the claiming club takes his contract. If he clears, the club can outright him to the minors and he has no say; he stays under club control on a minor-league deal. He would then be Rule 5-eligible and would hold XX-D rights against any future outright. Post-season: an outright after the September 1 cutoff ends his automatic eligibility. He could only return as an approved injury replacement, and only if he accepts the outright and stays on a minor-league reserve list in the organization without interruption; a release makes him ineligible for anyone this October.
- Designated for assignment: 7 days · Outright waivers · Article XX-D: the right to walk
- release him
- Release waivers cost a claiming club $1 but the claimant assumes the whole contract, so expensive players clear. The club owes the full unpaid balance of this season's salary, offset by whatever another club pays him this year. A released player is not post-season eligible for any club this year.
- Release waivers and termination pay · Which rate a split contract pays at release
- trade himBLOCKED
- Not now: players on major-league contracts cannot be traded after the Aug 3 deadline until the day after the World Series.
- Trade deadline · 10-and-5 rights · June 15 no-trade for free-agent signees
- renew him for next year
- Pre-arbitration: the club sets his 2027 salary near the minimum ($780,000 floor) and he has no leverage beyond a non-tender.
- Minimum salaries · Tender deadline
What the rules say about him
- Option years and the 20-day rule3 option years left entering 2026; 100 option days this season uses one (2 after 2026).A season with fewer than 20 days on optional assignment does not count as an option year, and those days count as Major League service. 2022-2026 Basic Agreement, Article XIX(E) and XXI(B), p. 98 (the number itself is in Major League Rule 7(c))
- Five optional assignments per seasonOptioned 4 times this season that count toward the cap of 5: 1 left.A player can be optioned at most five times in a season; a sixth trip requires outright waivers. 2022-2026 Basic Agreement, Article XIX(E), p. 98 (the number itself is in Major League Rule 7(c))
- Post-season roster eligibilityOn the 40-man before noon ET Sep 1. He stays eligible as long as he remains on the 40-man or 60-day IL through the post-season; an outright after the cutoff would end automatic eligibility.The post-season eligibility list is fixed at noon ET on September 1: everyone on the 40-man, the 60-day IL or the military list at that moment, who then stays there without interruption. 2022-2026 Basic Agreement, Attachment 25, p. 253 (the number itself is in Major League Rule 40)
- Rule 5 clockOn a 40-man roster (would first be exposed after 2025 otherwise).
Option years, season by season
| Season | Days on option | Option year used | Stints |
|---|---|---|---|
| 2026 | 100 | yes | Mar 9, 2026 to Apr 18, 2026 (24d, spring training)Apr 20, 2026 to May 13, 2026 (23d)May 15, 2026 to Jun 2, 2026 (18d)Jul 15, 2026 to Jul 22, 2026 (7d)Aug 18, 2026 to now (28d) |
Transaction log
| Aug 18, 2026 | Optioned | Athletics optioned RHP Mason Barnett to Las Vegas Aviators. |
| Jul 22, 2026 | Recalled | Athletics recalled RHP Mason Barnett from Las Vegas Aviators. |
| Jul 15, 2026 | Optioned | Athletics optioned RHP Mason Barnett to Las Vegas Aviators. |
| Jun 2, 2026 | Recalled | Athletics recalled RHP Mason Barnett from Las Vegas Aviators. |
| May 15, 2026 | Optioned | Athletics optioned RHP Mason Barnett to Las Vegas Aviators. |
| May 13, 2026 | Recalled | Athletics recalled RHP Mason Barnett from Las Vegas Aviators. |
| Apr 20, 2026 | Optioned | Athletics optioned RHP Mason Barnett to Las Vegas Aviators. |
| Apr 18, 2026 | Recalled | Athletics recalled RHP Mason Barnett from Las Vegas Aviators. |
| Mar 9, 2026 | Optioned | Athletics optioned RHP Mason Barnett to Las Vegas Aviators. |
| Aug 26, 2025 | Contract selected | Athletics selected the contract of RHP Mason Barnett from Las Vegas Aviators. |
| Jul 30, 2024 | Traded | Oakland Athletics traded RHP Lucas Erceg to Kansas City Royals for RHP Will Klein, RHP Mason Barnett and OF Jared Dickey. |
| Jul 24, 2022 | Signed | Kansas City Royals signed RHP Mason Barnett. |
Service through 2025 per FanGraphs RosterResource; options and this-season service reconstructed from the MLB transaction log (reconstruction; FanGraphs shows 3). Rule 5 exposure deadline Nov 17, 2026.