
Julio Cesar Mateo (born August 2, 1977) is a Dominican professional baseball pitcher. The 6’0 tall 220 lb Mateo bats and throws right-handed. He was signed by the Seattle Mariners as a non-drafted free agent on May 15, 1996.
Professional career
Seattle Mariners
Mateo went 4–2 with a 1.74 ERA in 15 games, including two starts, for Dominican Summer League Mariners in 1996. He tossed two complete games and earned one save.
In 1997 Mateo went 3–1 with a 3.30 ERA in 13 outings, including six starts, for Arizona League Mariners.
With the Short-Season Everett AquaSox in 1998, Mateo went 3–3 with a 4.70 ERA and four saves in 28 relief appearances. He also allowed one run over 11⁄3 innings in his lone outing for the Class-A Advanced Lancaster JetHawks.
Mateo went 1–3 with a 4.34 ERA and four saves in 20 outings for the Class-A Wisconsin Timber Rattlers in 1999.
Again with Class-A Wisconsin in 2000, Mateo went 4–8 with a 4.19 ERA and four saves in 36 outings, including one start.
He went 5–4 with a 2.86 ERA and a career-high 26 saves in 56 outings for the Class-A Advanced San Bernardino Stampede in 2001.
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2002-2007 |


| SO/BB | MLB | 2007 | 0.80 |
| SO9 | MLB | 2007 | 3.0 |
| BB9 | MLB | 2007 | 3.8 |
| HR9 | MLB | 2007 | 0.0 |
| H9 | MLB | 2007 | 9.0 |
| WHIP | MLB | 2007 | 1.417 |
| Fielding Independent Pitching | MLB | 2007 | 3.82 |
| ERA+ | MLB | 2007 | 120 |
| Batters Faced | MLB | 2007 | 52 |
| Wild Pitches | MLB | 2007 | 0 |
| Balks | MLB | 2007 | 0 |
| Times Hit by a Pitch | MLB | 2007 | 0 |
| Strikeouts | MLB | 2007 | 4 |
| Intentional Bases on Balls | MLB | 2007 | 1 |
| Bases on Balls/Walks | MLB | 2007 | 5 |
| Home Runs Allowed | MLB | 2007 | 0 |
| Earned Runs Allowed | MLB | 2007 | 5 |
| Runs Allowed | MLB | 2007 | 5 |
| Hits Allowed | MLB | 2007 | 12 |
| Innings Pitched | MLB | 2007 | 12.0 |
| Saves | MLB | 2007 | 0 |
| Shutouts | MLB | 2007 | 0 |
| Complete Games | MLB | 2007 | 0 |
| Games Finished | MLB | 2007 | 1 |
| Games Started | MLB | 2007 | 0 |
| Games Pitched | MLB | 2007 | 9 |
| ERA | MLB | 2007 | 3.75 |
| Win-Loss Percentage | MLB | 2007 | 1.000 |
| Loss | MLB | 2007 | 0 |
| Wins | MLB | 2007 | 1 |
| Wins Above Replacement for Pitchers | MLB | 2007 | 0.2 |