Sounds good...
*SPOILER ALERT*
Fumbles and holding the ball are not the main concern with Caleb.
#1. Ball security - Caleb Williams had a fumbling issue in college. Will that follow him to the NFL? We don't know. What we do know, is that every single NFL defense that plays him will make that their #1 target. Slapping the ball and trying to make him drop it. Hopefully this can be coached out of him. Luckily, CW didn't have an INT problem in college. Fingers crossed this holds over into the NFL. Though we all know the windows will be much tighter and will close faster than in college.
#2. Big game hunter - USC's defense couldn't stop a nose bleed. This forced Caleb to put the team on his back almost every game and hunt for the deeper connections instead of dumping the ball off for shorter completions and moving on to the next play. This was compounded by the fact that the offensive line was a sieve and forced Caleb off his mark more often than not. Once out of structure, Caleb has a tendency to big game hunt instead of just taking the easy completion. I found myself watching numerous games and saying, "throw it, THROW IT!" when seeing a guy open in front of him 8 - 12 yards down the field, only for him to hold onto the ball for another second or two before delivering what usually ended up being a strike to a guy 18 - 25 yards down field, consistently. I don't know if he'll be able to bring that to the NFL... but we've all seen it work for a certain player on the Chiefs.
#3. Off field distractions - Honestly most of this stuff seems to be rumors and other trash drummed up before the draft (probably to try to get him to slide down the boards). I think most if not all of it will be a non-factor once he enters the NFL and if it does rear its head, it won't be until he is well established. To me it would be a relief to go from decades of fans complaining about the on field play of our QB to merely complaints about off the field crap.
#4. Hero Ball - I list this, but only because some see it as an issue, thinking it won't translate to the NFL. Many a casual fan only look at the highlights of a player and his Hero Ball makes up all of his highlights. (Nobody is going to cut up a highlight film of him working within structure making simple reads, hitting slants and crossers) I think he was forced into hero mode out of necessity over propensity. I for one am glad he has it in his wheel house and has extensive real-world experience with it. It will easily make up 5-10% of his game in the NFL which could be the difference between winning and losing. It could also lead to him making mistakes and turning the ball over. Only time will tell.
#5. Occasional uncontested off-target throws - Sometimes for whatever reason, he misses throws. Short, intermediate and deep with zero pressure in his face. To be honest, I've seen every quarterback do this and I'm not worried about it affecting his overall game.