SANTA CLARA, Calif. -- Before the start of the San Francisco 49ers' offseason program back in April, all that coach Chip Kelly knew of running back Mike Davis is what he'd seen on tape from 2015.

What Kelly saw wouldn't have left a strong impression on anyone. Davis, a fourth-round pick in the 2015 NFL draft, averaged just 1.7 yards per attempt on 35 carries. In the process, he became just the sixth running back of the modern era to average less than 2 yards per carry with at least 35 attempts in a season. He also was held back by injuries, appearing in just six games.

But that Davis wasn't the Davis that showed up in Sunday night's preseason opener against the Houston Texans. For one, Kelly noted a major difference in size.

"Yeah, he’s a lot bigger in person," Kelly joked.

Davis was certainly much bigger than the video version of himself, but -- in reality -- he's actually a bit smaller than he was last season. Davis spent time in the offseason working to get leaner in the hopes that it would add some much-needed speed. Those efforts paid off for at least one night as he rushed for 72 yards on five carries, including a 44-yard burst on his first carry that showed off his new-found juice.

Before Sunday night, it had been hard to gauge whether Davis had made improvements in training camp. But with the pads on and live reps coming his way after Carlos Hyde and Shaun Draughn called it a night, Davis offered an emphatic statement that he is not only in the mix to nail down a roster spot but a contributor if the opportunity arises.

"I try to look at the positives with all those guys," Kelly said. "When I looked at film when we got here, it was just to give me a feel and a flavor for what he's like. I knew that he was a physical runner. I knew that he ran behind his pads really well, and he's shown that. He's really put himself in a position for a spot."

The 49ers are likely to keep as many as four running backs, with Hyde and Draughn locks to make the roster barring injury. After that, Davis will get competition from the likes of DuJuan Harris, Kelvin Taylor and Kendall Gaskins.

"It's like I talked to some of those guys in the locker room, you guys have a chance to play tonight," Kelly said. "You’re battling and what you put on tape is really what we're judging you on. Some guys really stepped up and really took advantage of that opportunity and some other guys were kind of looking around and kind of caught up in the moment. So they need to kind of settle down, take a deep breath and then hopefully everybody has a little bit better, kind of 'let's get going we have to get ready to go play Denver.'"

For Davis, more performances like Sunday's will put him in position to do more than just make the roster. He could also wipe away the memory of a forgettable rookie debut.