Five key players to keep an eye on during today’s 49ers preseason game vs. the Broncos in Santa Clara:• Blaine Gabbert, QB, No. 2
Coach Jim Harbaugh on Friday rejected the notion (that he created) of any murkiness at the backup position and threw support behind Gabbert. But Harbaugh has done that before with struggling players – A.J. Jenkins springs to mind – in an effort to boost their confidence and snap them out of their funk. Gabbert will be the second 49ers quarterback to enter the game and needs a far stronger showing than his 3-for-11 effort against the Ravens in the preseason opener. Gabbert drew a smattering of boos at Friday’s open practice at Levi’s Stadium. Another poor performance and they are sure to grow louder.• Chris Borland, LB, No. 50
He’s likely to start his second straight game but only because the 49ers are being cautious with Patrick Willis. Losing NaVorro Bowman is awful. Losing Bowman and Willis? Disaster. The undersized Borland is fun to watch because he darts about the field like a hyperactive terrier. Coaches want to see him hone that enthusiasm over the last three warmup games.• Joe Looney, G, No. 78
He didn’t get high marks in the preseason opener in Baltimore because, well, he played too high and got off balance. Looney seemed to remedy that issue during the ensuing three days of practice against the Ravens’ stubby defensive linemen. It will be interesting to see if he can put what he learned to practice against the Broncos. Meanwhile, Alex Boone’s training camp holdout is at 25 days and counting.• Jimmie Ward, DB, No. 25
No team attempted as many passes last season as the Broncos, which means the 49ers’ nickel defense ought to get plenty of work. As a result, fans ought to see a lot of the 49ers’ first-round draft pick, Ward, who has had a strong training camp. Opportunities in which Ward is matched against veteran receiver Wes Welker promise to be an excellent learning experience for the rookie.• Ian Williams, NT, No. 93
If the game resembles recent practices, Williams will get a smattering of snaps, including any along the goal line. He’s been seemingly unaffected by the leg fracture that sidelined him for so long. Still, there’s been little game-like physical contact in practices, and the Broncos’ offensive line ought to offer the push he needs to truly gauge his readiness.