SEATTLE -- The Most Valuable Player for the Toronto Blue Jays this season is yet to be determined. The final two months of the season will be the ultimate testing ground.

But as manager John Gibbons ruminated on Wednesday, there is no shortage of candidates.

Based on his performance on Tuesday as well as his glossy numbers, veteran right-hander Roy Halladay is near the top of the list. Halladay, who allowed two earned runs in seven innings in Tuesday's 12-3 victory over Seattle, is now 13-2 with a 3.06 ERA.

He is tied for the league lead in wins, fifth in ERA, tied for second in complete games (three), tied for first in fewest walks per nine innings (1.1) and has the league's best winning percentage (.867).

"Like any team, the ace is so important," Gibbons said. "You bank on at least 15 wins from him, but he does more for a team than just that. He stops bad streaks. I don't think anyone can afford to lose their ace. You saw what happened last year."

Halladay was 12-4 with a 2.41 ERA last season until he fractured his leg on July 8 against Texas. He missed the rest of the season. The Jays, who were 44-41 at the time and 5 1/2 games out of first, didn't not have the legs (or arms) needed down the stretch. They finished at 80-82, 15 games out of first.

Had Halladay remained healthy, perhaps he could have made a 10-game (or more) swing in the won-loss column. He has been particularly efficient at halting losing streaks. Since the beginning of 2005, the Blue Jays are 19-2 in the 21 games Halladay has started after a loss.

Halladay's numbers this season are comparable to his Cy Young Award season in 2003, when he went 22-7 with a 3.25 ERA as the anchor of the staff.

But as Gibbons points out, "I don't think you can really single one guy out." He mentioned three other veterans who are virtually irreplaceable, outfielder Vernon Wells, first baseman Troy Glaus and closer B.J. Ryan.

Wells, who returned to the lineup on Wednesday after missing two games with back spasms, is among the league leaders in seven offensive categories, including first in total bases (229) and extra-base hits (55). He leads the team in RBIs (78), stolen bases (11) and is tied with Glaus in home runs (26).

In his first season with the Blue Jays, Glaus has 72 RBIs to go along with his 26 home runs. He's on a pace for 44 home runs and a career-high 116 RBIs.

Ryan is just about an automatic save. He has saved 24 in 27 opportunities. He had a string of 18 1/3 scoreless innings (16 appearances) earlier this year. He has a 1.10 ERA and just 12 walks and 62 strikeouts in his 49 innings. He has given up just one home run and opponents are hitting .163 off him.

Rios to return? Another player who would have fit nicely into that MVP group had he not been injured (staph infection) this month is outfielder Alex Rios. He continues on a rehab assignment at Triple-A Syracuse.

Rios, who was 2-for-7 on the assignment with a walk and two strikeouts entering Wednesday's game, conceivably could return to the big club for the four-game Oakland series.

"There's a good chance," Gibbons said. "We'll see how he's going. He feels fine. His timing is a little bit off. The important thing is his ankle's fine."

Rios was hitting .330 with 15 home runs and 53 RBIs before he was placed on the disabled list June 28.

Jays' notes: Two pitchers coming back from injuries, left-hander Gustavo Chacin (strained elbow) and right-hander Ty Taubenheim (staph infection), both have been sent to Syracuse on rehab assignments. Chacin is scheduled to make his first appearance Sunday. ... For the second straight game, Gibbons posted two lineups before the game, one with Wells playing, and one with Wells on the bench. He waited until about a half hour before deciding on the one with his All-Star in the lineup. Wells went through a strenuous batting practice and felt good enough to play. Gibbons used him as the designated hitter. ... Despite their win on Tuesday, the Jays had won just four of their last 11 games at Safeco Field entering Wednesday's game. ... The Jays' .294 batting average after 100 games is the highest in club history this late in the season.

Up next: The Blue Jays continue their West Coast swing on Thursday when they travel to Oakland to open a four-game set against the A's at 10:05 p.m. ET at McAfee Coliseum. Ted Lilly (9-8, 3.89 ERA) will take on Joe Blanton (10-8, 4.90).