At an up-and-down 3-4, the reigning NFC champion San Francisco 49ers can't be reliably counted on as a bona fide contender. That makes Brandon Aiyuk's season-ending knee injury an outright disaster for a Bay Area constellation of football superstars still chasing an elusive Lombardi Trophy.

The news of Aiyuk being lost for the season to a torn ACL and MCL comes on the heels of the struggling 49ers already dealing with a rash of injuries to their skill group. There's ailing Deebo Samuel (illness), a hurt Jauan Jennings (hip), and the still-recovering Christian McCaffrey (Achilles). Plus, rookie Ricky Pearsall is still learning the ropes after missing the first part of the season while recovering from a gunshot wound.

It's needless to say, but a classic, top-flight possession receiver like Aiyuk was one of the last saving graces for both the 49ers and fantasy football managers:

If anyone can mitigate the loss of elite skill talent, it's Kyle Shanahan's 49ers, who probably have the best plug-and-play offense in the NFL. For example, I wouldn't necessarily be surprised to see Pearsall shine in the coming weeks in Aiyuk's role. The 49ers seem to make this kind of thing happen all the time.

The glaring issue for the 49ers is that you can only plug in holes and put a smile on your face to a certain degree. It's one thing to consider how to replace Aiyuk alone. It's another to also think about the plan without McCaffrey and the rest of San Francisco's best playmakers. You can only scheme up quality plays that don't need special players for so long.

No one in the NFL, not even the 49ers, has that much depth.

But for as bad as Aiyuk's season-ending injuries are for the 49ers as they try to stay above water, it's even worse for anyone who manages him in fantasy.

By no means is Aiyuk a top-five NFL receiver on his best day. But he is likely a foundational pick for many peoples' fantasy teams -- a guy who probably didn't make it past the third or fourth round at the absolute latest. Sure, part of the fun of playing fantasy in itself is finding replacements on the waiver wire for underperforming draft picks. However, you can't really do that for someone like Aiyuk, who was supposed to be one of your best players. That's a lot harder to recover from.

Without Aiyuk in the fold, we might start seeing the 49ers struggle in earnest. The same can be said for fantasy managers now scrambling to find viable replacement options at the near midseason mark -- if that's even feasible.

This article originally appeared on For The Win: Brandon Aiyuk’s knee injury is disastrous for the 49ers, even worse for fantasy football managers