SAN DIEGO -- Padres catcher Francisco Mejia is headed to Triple-A El Paso for a rehab assignment.

His health is only half of the equation.

By all accounts, Mejia's balky knee is close to full strength. His ice-cold bat is another issue.

"We'll get him consistent at-bats throughout the rehab assignment," said Padres manager Andy Green before Tuesday night's matchup with the D-backs. "How long that rehab goes is going to be, first and foremost, dictated by how his knee feels. Then it's also about finding his timing."

Mejia is one of the toolsiest young catchers in the sport. His quick bat, in particular, stands out. The 23-year-old has always projected as an excellent hitting catcher, and that’s why the Padres gave up Adam Cimber and Brad Hand to acquire him from the Indians.

With sporadic playing time over the season's first six weeks, Mejia slumped to a .167/.207/.259 slash line in 19 games before he landed on the injured list 10 days ago. The Padres want him to regain some of his swagger at the plate.

To be frank, they could use the offense. The San Diego bats have sputtered -- and nowhere more so than at catcher. Starter Austin Hedges and backups Mejia and Austin Allen have combined for a 38 wRC+, the second-worst mark in the Majors (ahead of only the Salvador Perez-less Royals).

Sure, catcher is clearly a defense-first position. But the league average wRC+ for backstops is 90 -- 52 points higher than San Diego’s mark. And the Padres don't have the luxury of an otherwise-deep lineup.

In that regard, Mejia's rehab stint represents an opportunity. Team sources indicated that if he hits at Triple-A, and if Hedges continues to slump, Mejia would be in line for a more regular role when he returns to the Padres. Simply put: They need offense from somewhere.

Green was more diplomatic about a potential battle for playing time.

"We'll continue to look at what we think is best for us to win every baseball game when he comes back," Green said. "If that means more playing time for him -- typically you earn more playing time by having high-quality level of at-bats and catching behind the dish."

Mejia's defense probably won't ever be on par with Hedges'. Once again, Hedges sits toward the top of the league in nearly every framing metric, and he's been excellent in most other facets. But entering play Tuesday, Hedges was hitting .176 with a .554 OPS.

Mejia's defense is shakier. His arm is elite, but he rates toward the bottom of the league in most framing metrics. Then again, he's 23 and hasn't been given a run behind the plate in the big leagues.

Of course, any uptick in Mejia’s playing time would first be predicated on him turning things around at the plate. In his brief time in the big leagues, he's been far too chase-happy. The Padres don't mind his aggression, but they'd like better quality at-bats.

"We want to see him be him," Green said. "He's a free-swinger, he's going to hit balls hard, he's going to hit all kinds of different pitches. We'd like to see him find that rhythm again."