The San Francisco 49ers didn't have to add to their running back group this offseason. The team already had Jerick McKinnon returning from an ACL injury and the player who replaced him last year, Matt Breida, ready to compete for playing time.

McKinnon was lost for the year before the regular season kicked off. Breida was banged up for most of the year but fought through the season. Raheem Mostert, who until last year was primarily a special-teams contributor, tried to take on some of the workload but a broken forearm ended his season.

Then the 49ers added Tevin Coleman. Now, the group is deep. Very deep. San Francisco could have one of the deepest running back groups in the league. Perhaps. That all depends on health and living up to potential, which seems to be a theme for the entire roster.

Fullback Kyle Juszczyk spoke with reporters on Saturday and discussed the surprisingly deep group of running backs, and what having so much talent means for the 49ers in 2019.

"I think all of them have a similarity in speed," Juszczyk said. "These guys are fast. But I do think they complement each other well and that they're going to be able to kind of spare each other when one guy maybe is a little tired. You're not losing anything by bringing in your second guy, your third guy, even our fourth guy. We feel like all those guys are at a starting-caliber level that there's really not much of a drop-off when one has to come out."

Juszczyk clarified that he doesn't think the 49ers have four of the same guy. Each running back has his own strengths, and head coach Kyle Shanahan will have no problem taking advantage of those strengths.

As for Coleman, Juszczyk has been impressed with the new addition.

"Number one, he works his tail off," Juszczyk said. "He really does. Just from a work standpoint, coming in here in the spring, that stood out to me right away. But as far as on the football field, I think he does an incredible job of running the wide zone, which includes pressing his blocks. You always hear about that one-cut kind of runner, and I think he's really good at that.

"The other thing is the guy finishes in the end zone. That was one thing I couldn't help but notice when we were watching Atlanta tape; the guy kept finishing in the end zone, and I feel like that's something that we missed. Having that is really going to add to our offense."

Shanahan says you can never have too much talent at one position. That was evident last year when the team started looking to its practice squad and street free agents for players who could fill in. That's why San Francisco decided to target Coleman in free agency when it saw he was available.

The addition wasn't a knock on McKinnon, who was supposed to be last year's featured back. Remember, Shanahan had to throw out a significant chunk of his playbook after the running back was sidelined for the season.

"We made a commitment to Jet [a year] ago to come in here and be our starting running back," Shanahan told reporters on Friday. "We had to decide between him and Carlos (Hyde), and we went with Jet, and we were excited about that. And he had such an unfortunate injury, and we had to go the year without him."

McKinnon started training camp on the team's physically-unable-to-perform (PUP) list. It was a precautionary move after the running back had what was described as a "flare-up" in his knee a couple of weeks ago.

"I expect Jet to be good to go soon and I think he'll be there for Week 1," Shanahan explained. "But, it's so nice that if just maybe not, that you do have some other guys where the pressure is not all on you, where he felt like it was a little bit last year."

Breida filled in admirably for McKinnon but had to deal with injuries himself. Still, he finished the year with a career-high 814 rushing yards on 153 carries with three touchdowns through 14 games and 13 starts. He also showed off his versatility by hauling in 27 passes for 261 receiving yards and another two scores.

"We were very excited with Breida as a backup going into that year, and he filled in great as a starter," Shanahan said. "But, he got banged up all year. We ended up having to go with our practice squad guys and play with four backs, and now we have four to start with that are starting-caliber guys. And we used four last year. So, the fact that we have four on our roster now is a very good thing to have."