You basically did on reading defenses and I think the mental part of the game is easier to overcome than the physical and you can get better with time and experience which he is getting right now.
Statements like this are inherently untrue.
Every athlete, or just individual for that matter, is unique. Every one has a threshold, or upper limit of what they can achieve across hundreds of possible skills and attributes whether that is physical, mental, speed, strength, vision, quickness, whatever.
Just like the upper threshold for EVERY possible attribute is unique to each athlete, so is the speed at which they might be able to improve it, and also the ease at which they improve it.
i.e. what might be easy to improve for one athlete, could be very hard for another. That's not meant as a statement for or against JM, just a fact about every athlete.
As for reading defenses, that's not just a mental aspect. It's way, way more than that. Yes, JM would need to know what the reads are for a lot of situations and that's a learning thing, but there is SO much more.
some very critical aspects of this are
1) overall quickness - being able to get a QBs entire body into position on schedule to look where he needs to look. This part is somewhat easier to train overall if an athlete has the aptitude. JM does have a LOT of work to do here as I have documented before.
2) Visual cortex - The ability for information to pass quickly from the eyes to the brain for further processing. This one is pretty hard to train and even harder to measure, but critical and is somewhat innate. This is why some players just seem to 'see' things that others don't. Until recently it was thought to be completely untrainable, but some recent research has found ways to make some improvements. For the record, I've never seen any type of link of this type of processing capability to overall intelligence - they seem to be independent attributes (i.e. someone could have a super high IQ but still have very low visual cortex processing speed, or someone could be dumb as a box of rocks, and yet have very high visual cortex processing speed)
3) field of vision - both depth and breadth at which visual information registers for processing by the cortex. So far, there isn't an established way to train this unless there's a known visual issue that can be fixed with contacts or surgery.
i've no idea where JM would stand on 2 and 3, but just mention those due to hearing statements last season that in meetings when asked what he was seeing on the field in certain situations, he wasn't sure or wasn't able to answer so those are key aspects of that equation.
Net - we really don't know how easy, or difficult it could be for JM to address anything because everyone is different. He might have a high or low overall ceiling in some areas, or have a high or low ability to improve it. Other QBs in the room likely have different thresholds for different attributes that are totally different from JMs.
