SANTA CLARA, Calif. -- The severe injury to San Francisco 49ers wide receiver Michael Crabtree occurred during a 7-on-7 drill Tuesday.
"He was coming in motion, planted and started a route and he said it felt like someone kicked him in the Achilles -- that's what most people say that feels like," 49ers coach Jim Harbaugh said, referring to Crabtree's torn Achilles tendon. "Good news is he woke up from the surgery and the first thing he asked the doctor how it went."
Running back Kendall Hunter had the same injury late last season, but the recovery won't be treated the same because of the timeframe involved, Harbaugh said.
With Crabtree out, second-year receiver A.J. Jenkins immediately takes on a more important role. The team's first-round pick in 2012 did not make a catch in his rookie season, spending most of the year inactive.
Jenkins said last season was "very humbling."
He came into OTAs at 196 pounds with the goal to get to 200 by the time the season begins.
"I was just working my butt off trying to put on some pounds and gain some weight this offseason," Jenkins said.
San Francisco traded with Baltimore for Anquan Boldin in the offseason after he caught 65 passes for 921 yards and four touchdowns for the Ravens in the regular season. Boldin went on to catch 22 passes for 380 yards and four touchdowns in the playoffs, including six for 104 yards and a score against the 49ers in the Super Bowl.
Boldin is not at the 49ers facility this week because of a prior commitment.
Two of San Francisco's other receivers -- Mario Manningham (knee) and Kyle Williams (knee) -- are coming off season-ending injuries but are expected to be back by the start of the season, if not earlier.
The team drafted Quitton Patten out of Louisiana Tech in the fourth round and it also returns Chad Hall, who finished the season on the 53-man roster, and Ricardo Lockette, who spent the majority of last season on the practice squad.
Crabtree was targeted more than twice as often as the 49ers' next most targeted player last season (Vernon Davis), but even without him quarterback Colin Kaepernick is remaining positive.
"We have a lot of talent out here," Kaepernick said. "We have a lot of great players."