The San Francisco 49ers gave Jerick McKinnon big money to be their lead running back this offseason. That reign atop the depth chart will be short-lived, as he left Saturday's practice with a season-ending knee injury. 

According to NFL Network's Ian Rapoport, McKinnon tore his ACL—which means Matt Breida and free-agent acquisition Alfred Morris are in line to receive major upticks in usage.

Here's a look at how their fantasy stocks should be viewed moving forward.

Alfred Morris

Morris has only been with the Niners for a few weeks, but he's now the favorite to serve as San Francisco's early-down back.

The career journeyman has experience playing in head coach Kyle Shanahan's outside zone running scheme dating back to his days with Washington, and he erupted for 1,613 yards and 13 touchdowns playing in that offense as a rookie in 2012.

Now, expecting some sort of repeat would be foolish. But based on that track record, it's hard not to be bullish on Morris' fantasy prospects.

As if that weren't reason enough to buy Morris stock, NBC Sports Bay Area's Matt Maiocco wrote Saturday that Breida "is likely to be the backup" even with McKinnon done for the year. 

At this rate, Morris should be viewed as a quality flex option with low-end RB2 appeal who could creep into a higher tier with a few solid showings to start the season.

Matt Breida

Breida flashed some skills as a runner and pass-catcher out of the backfield last season, rushing for 465 yards and adding another 180 in the passing game. He spent most of the year spelling Carlos Hyde, who left for the Cleveland Browns in the offseason.

Fantasy value here might come down to how comfortable the 49ers are with using Breida as more than a change-of-pace option. Listed at 5'10" and 190 pounds, Breida is a little slight for a three-down-back role. The Niners never gave him more than 12 carries in a game last season, and that should limit his upside here.

Breida is worth a pickup in any leagues where he's available; most shallower leagues have him available at this point.

For now, we have to consider Breida a flex option at best until he proves he'll get more than 12 to 15 touches a game.