Jerick McKinnon is a very good NFL running back. That's not being disputed.
The 49ers running back has rushed for at least 500 yards in three of his five NFL seasons.
But there's just something different about Raheem Mostert, whom the 49ers will place on injured reserve with a high ankle injury he sustained against the Los Angeles Rams last Sunday.
"It looks different on the field, for lack of a better phrase, he has three rockets up his butt, and he's arguably the fastest guy on the field every time he's on [the field]," NBC Sports NFL analyst Chris Simms told Grant Liffmann on Thursday. "It's hard to replace speed or emulate that."
While McKinnon has 211 rushing yards on 41 carries through six games this season, Mostert has 303 rushing yards on 51 attempts in parts of four games.
Mostert (75.8) is averaging 40 more yards a game than McKinnon (35.2). Mostert simply is on a different level than McKinnon.
"The same hole Jerick McKinnon sees and Raheem Mostert sees, Mostert sees it and goes go-go gadget legs and he turns it on and he can hit that hole and go through it before it ever closes," Simms said. "McKinnon sees it and he goes, 'There's the hole,' but just as he's getting four or five yards, it starts to close and he goes down."
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Mostert's lone rushing touchdown this season went for 80 yards on the first play from scrimmage against the New York Jets in Week 2. McKinnon doesn't even have 80 yards in any of his six games this season.
"That's why [Mostert is] so dangerous," Simms said. "He's the perfect fit for the [Kyle] Shanahan run scheme, where, yes, stretch them out, Shanahan will find a seam, then put your foot down and go 100 miles per hour through that hole. That's where it's the perfect match of player and scheme.
Shanahan told reporters Friday that Mostert will go on IR, meaning he will miss at least three games (Sunday at the New England Patriots, Nov. 1 at the Seattle Seahawks and Nov. 5 at home against the Green Bay Packers).
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While Mostert recovers, and Tevin Coleman and Jeff Wilson Jr. deal with injuries themselves, McKinnon and undrafted rookie JaMycal Hasty will have to carry the load
Hopefully for the 49ers, McKinnon can get through those holes Simms says he can't get through.