San Francisco 49ers quarterback Jimmy Garoppolo has noticed a much different Dante Pettis out on the practice field compared to a year ago. That bodes well for the second-year wideout and the 49ers offense, which lacked a single 500-yard wide receiver last season.

"He's coming out of breaks with power," Garoppolo told reporters this past week. "His speed, it doesn't look like he's moving very fast, but he really is. It's a weird thing for a quarterback to get used to. He's different than most guys running.

"Where Marquise (Goodwin) looks like he's running really fast — and he is running really fast — where Dante it's different. Being able to get on the same page as him I think these last couple of weeks and everything has been very important."

Pettis is always trying to find ways to improve his on-field play. He is a student of the game. Pettis is laid back, but also smart, always asking questions, and looking to soak up knowledge. He worked on his route-running, being more consistent in it, and learning how to better get in and out of his breaks.

Pettis didn't just focus on improving his on-field play this offseason. He also decided to add some mass to his frame. It was nothing dramatic — just about 10 pounds.

"I'm like 197 right now, which is a big jump from last year," Pettis said on June 4. "Last year, I finished the season like probably 188. I've just been putting on good healthy weight. I feel like my legs got a little bit stronger, all of that stuff.

"Realistically, I'll probably play this year right around 197; try to stay between 200 and 195."

Pettis dealt with a couple of knee injuries last season, which slowed his rookie development. He came on strong during the second half of the season after his initial setback but left a Week 16 game against the Chicago Bears before being placed on injured reserve and missing the finale.

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Pettis' added weight has nothing to do with injury prevention, the receiver insists. It was just another step in his development.

"I know I'm not the biggest guy," Pettis admitted. "I know I'm a little slimmer. That's something that I've always been trying to work on, just gaining a little bit more weight, get a little bit stronger.

"It doesn't really have too much to do with injury. I don't know, I never really got hurt until last season, and it was just kind of some freak things that happened. It's more being able to deal with the strength of the other players in the NFL."

Head coach Kyle Shanahan understands that a young receiver's impact isn't always immediate. For most, there is a big transition going from the college game to the pros.

"[The college game is] a lot more spread out," Shanahan explained this past week. "There's a lot more bubbles and things like that. The routes are a lot sloppier. There's not as much man-to-man and stuff. It takes a while to get used to that."

Shanahan exchanged text messages with Pettis throughout the offseason, hoping the receiver would return even more motivated than last year. Pettis would always respond the right way, but you never really know until you get to see a player face-to-face again.

"When I saw him the first week he got back, to see the size that he had put on — not that he's going to be real noticeably different to everyone — but he worked while he was gone," Shanahan continued. "He worked while he was away. He tried to get bigger. He worked more at his routes, and he came here with the idea of 'Hey, I'm not just coming here to get better back in shape. I'm coming here to get better.'

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"So, when he came back, he was in such good shape that since he's been here over these last two months, he's gotten better in every area."

Pettis did have a minor setback, tweaking his hamstring a few weeks ago. But the young receiver battled through the injury, and now has six weeks to get his body right before training camp.

Mentally, Pettis is a lot more comfortable. This offseason sure beats his rookie campaign, where he was seemingly used everywhere on the field. There didn't seem to be a set plan for him, which may have been true. Pettis believes he received a trial-by-fire initiation into the NFL.

"They moved me around a lot last year," Pettis said. "I feel like they were just kind of like, 'This is how you're going to learn.' Just throw me in there, move me around, and see what I can do. I think that, last year, me doing that so early helped me figure it out later on."

Pettis is grateful for the experience. He took 453 snaps, was targeted 40 times, and caught 27 receptions for 467 yards and five touchdowns with just one drop. Pettis ended the year as Pro Football Focus' fifth-highest graded rookie receiver with more than 15 targets. His yards per reception ranked second among rookie receivers with more than 10 targets, and quarterbacks had a passer rating of 125.7 when throwing his way.

"It started to kind of happen at the end of the season last year," Pettis said. "I was able to play a little bit more. The more you play, the more comfortable you get being the huddle, and actually hearing the crowd and looking over, seeing the defense, hearing the quarterback calling the play and stuff.

"The last few games, I felt a lot more comfortable with that. In the offseason, obviously, being able to just look back over the plays and getting the whole OTAs and stuff in, has definitely helped me learn the offense more."