Beck covered a Neil Young classic. That’s nice, right? One weary singer-songwriter icon saluting another? Beck comes from an alt-rock generation where everyone idolized Neil Young, and Beck himself is no exception. A few years ago, he and Jenny Lewis covered Young’s “Harvest Moon” at Red Rocks. Today, Beck has shared his own stripped-back acoustic take on 1972’s “Old Man,” which might be Young’s best-known song. But there’s a twist here, and that twist involves the National Football League.