Born 1971 · Weymouth, MA · age 55
General manager for the Red Sox (2020–2023).
4 seasons with salary-era data across 1 stint. All figures are franchise-level outcomes during the tenure, not solely attributable to one executive.
| Team | Role | Years | Szns | WAB | WAB/yr | TAB | WAR surp | HG | Trade | FA | R5 | AcqLev | W-L% | PO | Pen | WS | Surp $M |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ▸ Red Sox | GM | 2020–2023 | 3 | -7.2 | -2.41 | -13.1 | -57.4 | +21.1 | +13.3 | -44.9 | +7.2 | 1.70 | 0.498 | 1 | – | – | -239 |
| Career total (1985+ data) | 4 | -7.2 | -13.1 | -57.4 | +21.1 | +13.3 | -44.9 | +7.2 | 1.70 | 0.498 | 1 | – | – | -239 | |||
Acquired minus surrendered / signed minus walked.
Every roster slot ranked best→worst by WAR, averaged across Brian O'Halloran's seasons. Bars = his rosters; the black line = the league-average player at each slot. Staying above the line deep into the roster is the depth edge.
| Player | Pos | Team | How | Year | Szns | fWAR | WAR/yr | Lev |
|---|---|---|---|---|---|---|---|---|
| Wilyer Abreu | OF | BOS | Trade | 2022 | 4 | +8.3 | +2.1 | – |
| Ceddanne Rafaela | OF | BOS | Draft | 2023 | 4 | +7.9 | +2.0 | – |
| Nick Pivetta | P | BOS | Trade | 2020 | 5 | +7.9 | +1.6 | 0.3 |
| Garrett Whitlock | P | BOS | Rule 5 | 2020 | 6 | +7.6 | +1.3 | – |
| Brayan Bello | P | BOS | Draft | 2022 | 5 | +6.8 | +1.4 | – |
| Trevor Story | SS | BOS | Free agency | 2022 | 4 | +6.1 | +1.5 | 1.3 |
| Alex Verdugo | OF | BOS | Trade | 2020 | 4 | +6.0 | +1.5 | 1.9 |
| Enrique Hernández | OF | BOS | Free agency | 2021 | 2 | +3.9 | +2.0 | 18.7 |
| Rob Refsnyder | OF | BOS | Free agency | 2021 | 4 | +3.8 | +1.0 | 0.6 |
| Hunter Renfroe | OF | BOS | Free agency | 2020 | 1 | +2.6 | +2.6 | 12.9 |
| Kenley Jansen | P | BOS | Free agency | 2022 | 2 | +2.5 | +1.2 | 0.3 |
| Tyler O'Neill | OF | BOS | Trade | 2023 | 1 | +2.5 | +2.5 | 11.7 |
| Chris Martin | P | BOS | Trade | 2023 | 2 | +2.4 | +1.2 | 0.4 |
| Triston Casas | 1B | BOS | Draft | 2022 | 3 | +2.2 | +0.7 | – |
| Justin Slaten | P | BOS | Trade | 2023 | 3 | +2.2 | +0.7 | – |
| John Schreiber | P | BOS | Trade | 2021 | 3 | +1.9 | +0.6 | 0.5 |
| Masataka Yoshida | DH/OF | BOS | Draft | 2023 | 3 | +1.8 | +0.6 | – |
| Adam Duvall | OF | BOS | Free agency | 2023 | 1 | +1.6 | +1.6 | 0.4 |
| David Hamilton | 2B/SS | BOS | Draft | 2023 | 2 | +1.5 | +0.8 | – |
| Michael Wacha | P | BOS | Free agency | 2021 | 1 | +1.5 | +1.5 | 0.9 |
| Brennan Bernardino | P | BOS | Trade | 2023 | 3 | +1.5 | +0.5 | 0.2 |
| Connor Wong | C | BOS | Trade | 2020 | 5 | +1.4 | +0.3 | – |
| Justin Turner | 3B | BOS | Free agency | 2023 | 1 | +1.2 | +1.2 | 0.3 |
| Josh Winckowski | P | BOS | Draft | 2022 | 3 | +1.2 | +0.4 | – |
| Cooper Criswell | P | BOS | Free agency | 2023 | 1 | +1.1 | +1.1 | 5.1 |
| Garrett Richards | P | BOS | Free agency | 2021 | 1 | +1.1 | +1.1 | 5.6 |
| Martín Pérez | P | BOS | Trade | 2020 | 2 | +1.1 | +0.5 | 0.7 |
| Kyle Schwarber | DH/OF | BOS | Trade | 2021 | 1 | +1.1 | +1.1 | 5.5 |
| James Paxton | P | BOS | Free agency | 2021 | 2 | +1.0 | +0.5 | 0.3 |
| Christian Arroyo | 2B | BOS | Trade | 2020 | 3 | +0.8 | +0.3 | 0.0 |
| Reese McGuire | C | BOS | Trade | 2022 | 3 | +0.7 | +0.2 | 0.7 |
| Adam Ottavino | P | BOS | Trade | 2021 | 1 | +0.6 | +0.6 | 2.8 |
| Kevin Plawecki | C | BOS | Free agency | 2020 | 2 | +0.6 | +0.3 | 0.4 |
| Pablo Reyes | OF | BOS | Trade | 2023 | 1 | +0.5 | +0.5 | 0.2 |
| Chris Mazza | P | BOS | Trade | 2020 | 1 | +0.4 | +0.4 | 0.5 |
| Kevin Pillar | OF | BOS | Trade | 2020 | 1 | +0.4 | +0.4 | 0.6 |
| Austin Davis | P | BOS | Trade | 2021 | 2 | +0.4 | +0.2 | 0.8 |
| Matt Strahm | P | BOS | Free agency | 2022 | 1 | +0.3 | +0.3 | 0.2 |
| Raimel Tapia | OF | BOS | Trade | 2023 | 1 | +0.3 | +0.3 | 0.1 |
| Zack Kelly | P | BOS | Draft | 2022 | 2 | +0.2 | +0.1 | – |
| Chris Murphy | P | BOS | Draft | 2023 | 1 | +0.2 | +0.2 | – |
| Luis Urías | 2B/3B | BOS | Trade | 2023 | 1 | +0.2 | +0.2 | 0.1 |
| Jaylin Davis | OF | BOS | Trade | 2022 | 1 | +0.2 | +0.2 | 0.1 |
| José De León | P | BOS | Free agency | 2021 | 1 | +0.1 | +0.1 | 0.4 |
| Richard Fitts | P | BOS | Trade | 2023 | 1 | +0.1 | +0.1 | – |
| Joe Jacques | P | BOS | Draft | 2023 | 2 | +0.1 | +0.0 | – |
| Ryan Sherriff | P | BOS | Free agency | 2023 | 1 | +0.1 | +0.1 | 0.0 |
| Robert Stock | P | BOS | Trade | 2020 | 1 | +0.1 | +0.1 | 0.3 |
| Tommy Pham | OF | BOS | Trade | 2022 | 1 | +0.1 | +0.1 | 0.1 |
| Dylan Covey | P | BOS | Trade | 2020 | 1 | +0.1 | +0.1 | 0.1 |
| Taylor Motter | SS | BOS | Trade | 2021 | 1 | +0.1 | +0.1 | 0.5 |
| Mauricio Llovera | P | BOS | Trade | 2023 | 1 | +0.1 | +0.1 | 0.0 |
| Abraham Almonte | OF | BOS | Trade | 2022 | – | -0.0 | – | – |
| Yu Chang | SS | BOS | Free agency | 2023 | 2 | +0.0 | +0.0 | 0.1 |
| Jake Faria | P | BOS | Free agency | 2023 | – | -0.0 | – | – |
| Marwin González | SS | BOS | Free agency | 2021 | – | +0.0 | – | – |
| Jonathan Lucroy | C | BOS | Free agency | 2020 | 1 | +0.0 | +0.0 | 0.0 |
| Yairo Muñoz | SS/OF | BOS | Free agency | 2020 | 1 | -0.0 | -0.0 | 0.4 |
| César Puello | OF | BOS | Free agency | 2020 | 1 | +0.0 | +0.0 | 0.1 |
| Yolmer Sánchez | 2B/3B | BOS | Free agency | 2022 | – | +0.0 | – | – |
| Domingo Tapia | P | BOS | Trade | 2020 | – | -0.0 | – | – |
| Brandon Walter | P | BOS | Draft | 2023 | 1 | +0.0 | +0.0 | – |
| Phillips Valdéz | P | BOS | Trade | 2020 | 2 | +0.0 | +0.0 | 0.1 |
| Deivy Grullón | C | BOS | Trade | 2020 | 1 | +0.0 | +0.0 | 0.0 |
| Stephen Gonsalves | P | BOS | Trade | 2021 | 1 | +0.0 | +0.0 | 0.2 |
| Richard Bleier | P | BOS | Trade | 2023 | – | -0.1 | – | – |
| Michael Feliz | P | BOS | Free agency | 2021 | – | -0.1 | – | – |
| Jack López | 2B | BOS | Trade | 2021 | – | -0.1 | – | – |
| Joely Rodríguez | P | BOS | Free agency | 2022 | – | -0.1 | – | – |
| Austin Brice | P | BOS | Trade | 2020 | – | -0.2 | – | – |
| Matt Dermody | P | BOS | Free agency | 2023 | – | -0.2 | – | – |
| Frank German | P | BOS | Draft | 2022 | – | -0.2 | – | – |
| Matt Hall | P | BOS | Trade | 2020 | – | -0.2 | – | – |
| Danny Santana | OF | BOS | Free agency | 2021 | – | -0.2 | – | – |
| Hirokazu Sawamura | P | BOS | Draft | 2021 | 1 | -0.2 | -0.2 | – |
| Enmanuel Valdez | 2B | BOS | Trade | 2022 | 1 | -0.2 | -0.2 | – |
| Jeter Downs | 2B/3B/SS | BOS | Draft | 2022 | – | -0.3 | – | – |
| Connor Seabold | P | BOS | Trade | 2020 | – | -0.3 | – | – |
| Tyler Danish | P | BOS | Free agency | 2022 | – | -0.4 | – | – |
| Zack Godley | P | BOS | Free agency | 2020 | – | -0.4 | – | – |
| Robinson Leyer | P | BOS | Trade | 2020 | – | -0.4 | – | – |
| Kaleb Ort | P | BOS | Rule 5 | 2020 | – | -0.4 | – | – |
| Hansel Robles | P | BOS | Free agency | 2022 | 1 | -0.6 | -0.6 | 2.1 |
| Vaughn Grissom | 2B | BOS | Trade | 2023 | – | -0.7 | – | – |
| Corey Kluber | P | BOS | Free agency | 2023 | – | -0.8 | – | – |
| Franchy Cordero | 1B/OF | BOS | Trade | 2021 | – | -1.2 | – | – |
WAB = wins above what the team's payroll predicted (resource-controlled). WAR surplus = era-neutral value (WAR minus payroll in win-equivalents). Roster surplus $M = dollar value of WAR over cost. Build channels (realized fWAR): HG = home-grown via amateur draft / international signing; Trade = acquired minus surrendered (incl. purchases/waivers); FA = signed minus walked; R5 = Rule-5 / minor-league-draft pickups. Credit follows the acquisition year — home-grown to the regime at the player's draft/signing (not whoever was in the chair when he peaked), trade/FA/R5 to the GM who made the move. Players acquired as prospects before debuting (e.g. Smoltz, Bagwell; Rule-5 picks like Uggla) are counted as trade/R5, not home-grown. All are franchise-level outcomes during the stint, not solely attributable to one executive.