Anyone else notice how much fun he had soloing in the early days compared to now? Today he only has fun on the stage when the other band members are playing (99%). 
Yes, at that time Mark was into a guitar hero attitude in obvious search of some virtuosity.
But I think he already had changed at the time of his collaboration with Chet.
Of course during these years he had still the ability of playing faster than now and I think these were the best time because he really seemed to master the way he played his instrument, no more in targeting more velocity just for it but able to do so only when accurate. After the motorcycle accident Mark started to show here and there some sign of struggling, before it became obvious in the recent years.
