Blaine Gabbert to start, 49ers do more than ponder keeping three QBs on 53-man roster

SANTA CLARA, Calif. -- The San Francisco 49ers cut 20 players, made two trades, waived another player who was injured and placed another on the reserve/suspended list on Saturday, trimming their roster to the NFL-mandated 53 players. Here’s a closer look at the roster moves:

Most significant move: The biggest move of the day had nothing to do with cuts. San Francisco coach Chip Kelly announced that Blaine Gabbert will indeed be his starting quarterback on Sept. 12 against the Los Angeles Rams. Additionally, Kelly said Colin Kaepernick will be Gabbert's backup. That was supposed to be the quarterback competition during this preseason, but it never really materialized because Kaepernick missed two preseason games and a week and a half of practice because of right shoulder tightness.

Most significant non-move: The 49ers not only kept Kaepernick as expected, but they also kept a third quarterback in Christian Ponder. Kelly has been a proponent of keeping three signal-callers and keeping Ponder is a wise move in this case. Although he did it against backups, Ponder played well in Denver and San Diego and gives the 49ers another veteran presence. With Gabbert starting, it also gives the Niners some insurance if Kaepernick has injury issues again.

Wideout help wanted: The 49ers kept just five receivers, trading an undisclosed draft pick for Kansas City's Rod Streater on Saturday afternoon. That leaves a group of Torrey Smith, Quinton Patton, Jeremy Kerley, Streater and Aaron Burbridge on the roster. That's not a very inspiring group, so it stands to reason the Niners will keep their eyes open on the waiver wire for additional receiver help. One name that could be worth watching is Cecil Shorts, the former Texan and Jaguar, who had some success with Gabbert in their time together in Jacksonville.

Preseason stars come up short: Outside linebacker Marcus Rush was probably the team's most productive player in the four preseason games, coming up with six sacks (most in the NFL), a forced fumble and an interception. Defensive tackle Garrison Smith also performed well, posting 15 tackles including five for loss. Alas, it wasn't enough for either to land a spot on the roster. Rush got squeezed out as the team kept just three outside linebackers, but defensive lineman Ronald Blair can also help there if need be. Smith was left out in large part because the team has to carry Glenn Dorsey on the active roster until he can recover from knee surgery. Rush and Smith spent time on the practice squad a year ago and the Niners would probably like to bring both back in the same role, but after such strong performances, it's no guarantee they'll clear waivers.

49ers moves: Released WR Devon Cajuste, DL B.J. McBryde, WR Ryan Whalen, LB Corey Lemonier, DT Smith, DT Demetrius Cherry, RB Kelvin Taylor, TE Je'Ron Hamm, LB Shayne Skov, OL Colin Kelly, WR Bryce Treggs, WR Dres Anderson, QB Jeff Driskel, LB Marcus Rush, RB DuJuan Harris, CB Prince Charles Iworah, OL Norman Price, WR DeAndrew White, OL Fahn Cooper and OL Alex Balducci. In addition to trading for Streater, the 49ers also waived/injured WR DeAndre Smelter, traded S L.J. McCray to Seattle and placed outside linebacker Aaron Lynch on the reserve/suspended list.