The Sports Xchange

SANTA CLARA, Calif. — Even while ranking among the worst teams in the NFL this season, the San Francisco 49ers had fared well on the trainer’s table.

They hadn’t suffered a significant injury to a prominent player … until Thursday night.

That’s when safety Antoine Bethea, voted the team’s Most Valuable Player in 2014, suffered a season-ending pectoral tear in his upper right chest. The 10-year veteran was placed on injured reserve Friday.

The injury occurred, not coincidentally, as Bethea was committing a defensive infraction while attempting to tackle Seattle Seahawks wide receiver Doug Baldwin.

As Baldwin was running past Bethea after catching a pass, the veteran safety reached back with his right arm in an attempt to corral his opponent around the shoulders.

Instead, Bethea’s hand got caught on Baldwin’s face mark — a penalty — and jerked his own shoulder awkwardly. Bethea left the game immediately and never returned.

An MRI taken Friday revealed the full extent of the injury.

Bethea was replaced by rookie Jaquiski Tartt, who didn’t respond quickly enough to a play-action fake by Seahawks quarterback Russell Wilson on the very next play.

Instead of retreating to provide help in deep coverage, Tartt watched as Seahawks speedster Tyler Lockett ran past him for a 43-yard touchdown that increased the Seattle lead to 17-0 in the second quarter.

The 49ers went on to lose the game 20-3.

REPORT CARD VS. SEAHAWKS

–PASSING OFFENSE: D-minus. The 49ers got tight end Vernon Davis (four catches, 61 yards) significantly involved in the offense for just the second time this season in Thursday’s loss to Seattle. So much for the good news in the passing game. The offensive line allowed six sacks, wideout Torrey Smith never caught a pass against defensive star Richard Sherman’s coverage, and Colin Kaepernick was held to 124 yards after having averaged 301 in his previous two games.

–RUSHING OFFENSE: F. The 49ers’ only real chance to beat the Seahawks was to get their ball-control offense going against them. That never happened. Carlos Hyde was limited to 40 yards on 11 carries, and backup Reggie Bush did more harm (a key drop on the first possession of the game) than good (34 total yards). The 49ers were so clueless in the running game, they couldn’t even figure out a way to get quarterback Colin Kaepernick a carry for the first time in his career.

–PASS DEFENSE: B-plus. Limiting Russell Wilson to one touchdown pass, sacking him five times and intercepting him twice is “A”-caliber work. But the 49ers proved somewhat vulnerable to big plays in the Seattle passing game, including a 43-yard bomb for a touchdown to rookie wideout Tyler Lockett in the second quarter. Wilson averaged a chains-moving 13.1 yards on his 18 completions.

–RUN DEFENSE: B. The 49ers made Seahawks star running back Marshawn Lynch work so hard, he threw up on the sideline. Unfortunately, that came after he’d scored a one-yard touchdown on Seattle’s first offensive series of the game. It took Lynch 27 carries to get 122 yards, which translates to an admirable defensive effort.

-SPECIAL TEAMS: B. If only every 49ers unit were so consistent. The 49ers were unspectacular, but mistake-free, in their returns; kicker Phil Dawson made all his field-goal attempts (unfortunately, he had only one) and punter Bradley Pinion was busy (nine kicks for a 43.3-yard average).

–COACHING: F. During a long wait for head coach Jim Tomsula to make himself available to the media after the blowout loss, some reporters wildly speculated the delay was being caused by the first-year coach’s firing. You have to wonder if the front office is considering it. This says it all about the current state of the 49ers: They’ve been swamped 67-10 by division rivals Seattle and Arizona, two teams with whom they routinely competed — and often beat — in recent years.