I think, more than technique, it's his age. Even 100 years back top players hardly played Test at 45, many of them retired even from FC Cricket. His technique was never great, but workable in his 20s/30s; but this was bound to happen at some point - he helped it by stressing his career. There are players with poor technique dominating the game, best example can be Smith, but he won't be Smith if he carries till 45; in fact I believe he'll retire before 38 - that's 10 years from now.
I don't buy the idea of PCB's request to stick for few more Series, that forced him to carry on - when I left BD for Canada, they offered me almost double for 1 more year as consultant, just to finish their on going projects - I knew in that way, I'll never be able to immigrate. No way, I could replace that earning in Canada & in BD, one after another opportunity will come, until my PR Visa expires - a person should know his limits & his desire, what he wishes to do.
Misbah knows his limit but his desire was to carry on - got exposed; no one could have stopped him retiring after UK tour, if he wished. Viv played a blasting 60 in his last innings - 6 months before the 1992 WC, but he knew his legacy will be tarnished if he goes to AUS at almost 40; there is not point Viv Richards playing like Sherwin Campbell - he retired all of a sudden & didn't allow anyone to "request" him for one more try. I see lots of harsh words for Misbah including from myself, which he actually deserves now, for that, Misbah allowed people to "request" him.