Niners coach Jim Harbaugh said that wide receiver A.J. Jenkins has to pick it up. Wide receiver Anquan Boldin wasn’t happy with the 49ers’ four turnovers in the exhibition opening loss to the Broncos. When asked about them he said “You put on this uniform you’re expected to take care of the ball” Boldin told Phil Barber of the Santa Rosa Press Democrat. “That’s day one stuff.” That was a not so subtle shot at Jenkins who fumbled after catching his first pass of the preseason. Even quarterback Colin Kaepernick said Jenkins needs to step up. Nevertheless Jenkins has a fan despite the slow start he’s made on his NFL career. “I really like A.J. Jenkins” tight end Vernon Davis volunteered on his own on Monday. “He’s still learning the game. … He really wants to do well and succeed. He will get there and will be prepared by the start of the season.” Davis had a discussion with Jenkins and told him to get more serious about his approach.