So I have questions about the legality of the Caleb Williams 4th and 1 play.
 

First things first, the play obviously should’ve been whistled dead as the runner’s forward progress was not only stopped, but the defense pushed him back atleast 3 yards, but ignoring that fact. When is a loss of possession by a player considered a fumble? I’ve been thinking about different factors all morning and can only determine a that fumble, generally a pretty simple concept, can only occur when there is a combination of several unrelated factors. Some of my internal monologue:

A forward pass can occur when the ball carrier hasn’t fully passed the line of scrimmage, and there hasn’t been a prior forward pass in the sequence,

therefore if we consider this a “pass” it is a legal pass, but what’s the difference between a pass and a fumble? Obviously when a passer loses possession of the ball during a pass attempt we look at the arm motion of the passer, but there was no arm motion in this scenario, the ball is literally stripped out of the ball carrier’s hands. If a player from the other team stripped the ball in the exact same manner we would call that a fumble. Does that mean a player from the same team can’t cause his teammate to fumble? Well what if Caleb Williams sripped the ball or simply ran into his teammate but the ball instead fell to the ground where Caleb picked it up. Would it be a fumble in this case? Of course it would (it may go down statistically as a forced fumble by the nearest defensive player like sacks do when a qb gives himself up behind the los, but thats an entirely different topic/argument). So a teammate can cause a fumble. Does that mean the ball has to contact the ground in order to be a fumble? Well no because again if a player from the opposing team stripped the ball in the exact same manner it would be considered a fumble. So this is where my question arises. If a teammate can cause a fumble, how do we determine what’s a fumble? Wouldn’t intent have to factor into this discussion? We know laterals aren’t generally considered fumbles until they are received by unintended targets, and if the lateral hits the ground and a teammate recovers it is considered a fumble, which would make this play illegal and unable to be advanced since it was fourth down. But wait, this wasn’t lateral it was a pass right? Would that mean every time a player strips the ball carrier behind the line of scrimmage it’s then an interception not a fumble because maybe it was a pass? Can a fumble only occur beyond the line of scrimmage? When a qb drops the snap is it a fumble? And this only matters because it was 4th down and the ball wouldn’t be able to be advanced. There are other rules that take into account intent, they often times wave off intentional grounding if the passer was hit during the pass and the ball went somewhere unintended, and they also don’t call you for tripping if you fall and a player trips over you without you intending to trip them.
 

TLDR: That was a strip fumble and Williams shouldn’t have been allowed to advance the ball.

Any thoughts or do I sound crazy?