SAN DIEGO —— The final 36 games of this season could be a litmus test for Miguel Olivo.

The 27-year-old catcher with great potential has failed two big-league tests —— 2003 with the White Sox and last season with the Mariners.

Once again, after joining the Padres in a trade July 30 that sent Miguel Ojeda to Seattle, Olivo finds himself in the exam room. His final marks may determine what the Padres do with veteran catcher Ramon Hernandez, who is a free agent at the end of the season.

So far, Olivo has graded out very well.

Since joining the team, he has started 16 games, showing a strong arm, good speed and occasional power.

"I always liked him when he was with the White Sox," Padres manager Bruce Bochy said. "He's playing like we thought he could. He plays with energy. he has some pop in his bat, and he's a good receiver.

"The pitching staff has a sense of comfort with him. He has stepped in and done a great job. He has helped stabilize this team behind the plate, and given us some offense, too."

Olivo has always carried the "great potential" tag. Signed by Oakland as a free agent in 1996, he was traded to the White Sox in 2000. He made it to the big leagues in 2002 and played in 114 games for Chicago in 2003, hitting .237 with 19 doubles, six homers and 27 RBIs.

He was hitting .270 after 46 games with the White Sox last year when he was traded to Seattle, and his season went south from there. He missed two weeks after a surgical procedure to remove a kidney stone and hit just .200 in 50 games for the Mariners.

He batted just .151 in 54 games with the Mariners this season and .233 in 24 games with Triple-A Tacoma.

In part, his scouting report reads: "Cannon arm. Solid hitter who has improved his approach, becoming somewhat more selective. Has excellent speed for a catcher. Has shown power at times throughout his career. Must continue to improve his receiving skills and ability to handle major-league pitchers."

In his time with the Padres, he's hitting .292 with four home runs, three doubles, a triple and 11 RBIs. Project those numbers over a full season, and you're talking 25-30 homers and 75-90 RBIs.

He has shown a strong arm, picking off two runners, and drawn praise from the pitchers for his handling of the staff.

For as good as Olivo has been, he has made a few mistakes. He's run into several outs on the bases and thrown a couple of balls into the outfield, so not everyone is convinced he's the Padres' long-term answer behind the plate.

"He's a scout's delight, but a coach killer," said one National League scout. "From a scout's standpoint, he has a plus-plus arm, plus power and plus speed for his position. And (at 6-foot, 200-pounds) he has a good, solid body.

"He has all the tools scouts love. You can give him great grades on a report card and look great because everyone can see the talent. He has an awful lot of talent, a lot of potential, but he has never gotten it done consistently. Maybe this time it will be different because the Padres have a lot at stake when they make a final decision on him."

The Padres have been down the "potential" road behind the plate before.

Until Hernandez arrived in a November 2003 trade for center fielder Mark Kotsay, the catching position had been a revolving door of potential candidates.

Gary Bennett was the lead man in 2003. Wiki Gonzalez, a young player with great tools and a ton of upside, was the man in 2002 and 2001. Ben Davis got his shot in 2000. Journeymen Greg Myers and John Flaherty saw time in the late '90s.

Humberto Quintero was supposed to be the answer in the Padres' catching problems in 2003, but he never passed muster.

The switch-hitting Davis was a first-round draft pick in 1995 and was in the big leagues in '98.

He had the same tools as Olivo, but failed numerous tests and was finally traded to Seattle in a deal that brought pitcher Brett Tomko, journeyman catcher Tom Lampkin and infielder Ramon Vazquez to the Padres.

Oddly enough, the Mariners traded Davis to the White Sox last June in a deal that involved Olivo.

Now Olivo is with the Padres, and he's the main man in a pennant race, pushing the team's other catchers —— David Ross and Robert Fick —— to the bench.

"My dream is to play every day for a winning club," Olivo said. "This is my chance to show what I can do. But Ramon Hernandez is the man here."

Hernandez, however, is on the disabled list after have surgery on his wrist. Hernandez said Wednesday that he's not sure when he'll play again. He may not play for the Padres again this season, but will certainly demand top dollar on the free-agent market.

With closer Trevor Hoffman and right fielder Brian Giles heading a free-agent list that also includes third baseman Joe Randa, utilityman Mark Sweeney and pitchers Chris Hammond and Rudy Seanez, Padres officials may choose to spend their money on players other than Hernandez.

"I try not to think about the future," Olivo said. "When I got traded to San Diego, I knew Ramon was hurt, and figured if they traded for me, I'd get a chance to play. And I'm ready to play every day.

"I talk about catching, pitchers and hitting with Ramon and Carlos (new Padres bullpen catcher Carlos Hernandez) every day, and they have been a big help.

"All I can do is the best I can, work hard every day and see what happens."

Contact staff writer John Maffei at (760) 740-3547 or jmaffei@nctimes.com.