Phil,
I do not believe the par 3s are the weakest link at Muirfield. IMO, if any holes are less than phenomenal, it would be the two par 5s, and that is with the normal tees they use. They are roughly the same distance and are tee to green roughly the same direction. They are well guarded by traps for the tee shot, second (if necessary) and approach.
With only three exceptions, every green at Muirfield is guarded left and right by at least one bunker.
This is how the card list's the par 3s:
#4 182
#7 147
#13 156
#16 186
In my experience (roughly 20 rounds), the tees do not move much on #16 or #7. #7, however can be moved back to 165 or up to about 125. However, there's a back tee frequently used on #4 that's 210 or 215. #13 can play between 130 and 175. Depending on what the committee determines, there can be great variance in distance or very little. Options are available.
Regarding Mr. Els, he put himself in trouble. However, the holes were not so difficult that he shot himself out of the tournament, nor were they so easy that nothing short of a great shot kept him in it. 13 and 15 were also pivotal for Faldo in 92. He 3 putted 13 and made a fabulous up and down from behind 16.
Steve