I love how your argument is "weak on the puck". Something that you cant provide real substantial data on. From my eyes, Donato has made some very slippery plays and shows great speed. All while not looking weak on the puck.
Weak on the puck means when you are trying to go by a defender, you go into puck protection position (putting your body between the puck and the defender), but due to lack of strength, the defender knocks you off balance and is able to take the puck away more often than not.
That is what happens to Donato, causing frequent loss of possession.
Peter Forsberg was an extreme example of a player that was strong on the puck, this video is a great example of what that looks like when he has a defender draped all over him trying to knock him off the puck, but it's the defender that goes down while Forsberg continues skating and creates the goal.
I'm not asking him to be Peter Forsberg, but I'm asking him to not get knocked off the puck most every time he tries to puck protect. Help maintain possession instead of turning it over due to it.
Fiala is strong on the puck, Donato is not.