SANTA CLARA -- The 49ers just lost 19-13 to the Tennessee Titans in preseason game No.1. Here are their grades.QUARTERBACKS: C-PLUSKurtis Rourke outplayed Cam Ward until he injured his rib running between the tackles trying to score a touchdown in a preseason game. More on that decision in a minute. Rourke finished the night completing 12 of 14 pass attempts for 101 yards, and posted a respectable passer rating of 96.7. He saw the field well, got rid of the ball quickly, avoided a sack, scrambled for a first down and made a beautiful deep throw to De'Zhaun Stribling up the right sideline. Rourke looks like he has potential to develop into a quality backup or maybe even a starter. Too bad the 49ers got him injured. His replacement, Adrian Martinez, was awful.RUNNING BACKS: DNone of these running backs will make the team, nor should they. They're all mere camp bodies. The best one tonight was Sincere McCormick, who was quick and ran hard, but averaged a mere 3.8 yards per carry. In fairness to him and the other running backs, who aren't really worth naming, they kept getting hit in the backfield, which means they never really had a chance.WIDE RECEIVERS: B-MINUSDe'Zhaun Stribling was by far the 49ers' best receiver, but that's not saying much considering all their veterans sat out. That made Stribling the focal point of the offense, and he responded well, catching 7 of 8 targets for 63 yards. He doesn't create a ton of separation, which means he might not be the best option to move the chains on short passes, but he has outstanding hands, he catches the ball far away from his frame, and he's a true deep threat on a team that needs one. It will be interesting to see if he opens up Brock Purdy's downfield-passing game. The second-best wide receiver in the game for the 49ers was Jordan Watkins, who caught STATS.TIGHT ENDS: FMade almost no impact. It's really too bad the 49ers haven't drafted a tight end since Cam Latu.OFFENSIVE LINEMEN: DThe 49ers have a real problem at left guard, considering they don't have a starter at that position. The favorite to start is Robert Jones, who played tonight and was awful both in the run game and the pass game. And he's their best option. The 49ers need rookie Carver Willis to grow up quickly and take this job. He played most of the second half and performed better than Jones, which isn't saying much.DEFENSIVE LINEMEN: DRookie Gracen Halton was the star of this group. He stood up to double-teams in the run game and recorded a tackle for loss and a sack that was called back due to a penalty away from the play. The rest of the defensive line was horrible. Alfred Collins got pushed around, and Romello Height made no impact as a run defender or a pass rusher. In fact, veteran camp body Ogbonnia Okoronkwo was much more impressive than Height, which is troubling. Once again, the 49ers will be extremely reliant on Nick Bosa to be durable and dominant, two things he might not be able to provide anymore.LINEBACKERS: C-PLUSTatum Bethune was solid as usual. He's an excellent backup middle linebacker. Nick Martin played most of the game, which probably isn't a good sign for his chances to start at outside linebacker. Maybe the 49ers wanted to showcase him to the Titans so they'll trade for him, considering Robert Saleh drafted him last year. Martin's biggest play was a 15-yard penalty against him. He still doesn't seem to know what he's doing. As opposed to rookie Jaden Dugger, who didn't play like a rookie. Don't be surprised if he becomes the 49ers' third linebacker by the end of the season.DEFENSIVE BACKS:Jack Jones left the game early with a hand injury, rookie Ephysians Prysock replaced him and promptly broke up a potential touchdown pass intended for rooke first-round pick Carnell Tate in the front-right corner of the end zone. Prysock engulfed him, made him look tiny. He has serious potential. None of the other defensive backs stood out, with the exception of Ashtyn Davis, who nearly intercepted Cam Ward.SPECIAL TEAMS: CThe 49ers have an outstanding kicker -- tonight, Eddie Pineiro made a 52-yard field goal, easy. Like breathing. Unfortunately for the 49ers, they don't have a punt returner.COACHES: DI usually don't grade the coaches during the preseason because they don't game plan. They're coaching to evaluate certain players, not to win. And yet, for some strange reason, Kyle Shanahan and Klay Kubiak decided to call a quarterback draw for Kurtis Rourke from the four-yard line. It's always risky to run a quarterback between the tackles near the goal line, and on this play, Rourke injured his ribs. It's unclear how much time he'll miss. Fortunately, the 49ers also have Mac Jones to back up Brock Purdy. But Rourke seems extremely promising for a young quarterback. He's big, he's accurate and he's mobile. Now, the 49ers just have to keep him healthy. Easier said than done for them.Add us as a preferred source on GoogleFollow