Muller and Linden were both talented players who, if they had played in weaker eras (like the early decades of hockey), would've both been easy hall-of-famers. If you watched these guys at their respective bests, it was very easy to see why they both were drafted 2nd overall.
Both of them, though, had obvious limitations that kept them from being bigger stars than they were.
Starting with Muller, he was somewhat of a phenom when he was young, and I suspect he would have received Exceptional status in the OHL if it had existed when he played. As it was, he was able to play for his hometown team when he was 15, and scored a lot when he was 16 (of course, there was an even bigger phenom down the St. Lawrence in Montreal in the same draft - and one year older - so Muller still would've been overshadowed).
I really liked Muller a lot when he played in Montreal. He was at his best in '93, and often looked like the best Habs forward since Lafleur. His greatest strengths were his general hockey smarts (he was a natural); his positioning in almost all situations; his play in tight areas on the ice; a very good puck carrier; a very good passer; and pretty good defensively (smarts, positioning, and use of stick were all good).
He could quite frequently appear to "outplay" some of the biggest superstars of the League. However, the results in the form of scoring (or preventing scoring) sometimes didn't match how he looked, and sometimes didn't match his obvious effort, which usually was very strong.
I think it comes down to the fact that he wasn't outstanding in any one skill - skating, goal-scoring, passing, puck-carrying, defense. And I think when he started to get some injuries, his lack of virtuoso skills became more apparent.
He was very, very good for the Habs in '93 and I don't think they would've won the Cup without him.
With Linden, early in his career he could often look extremely good: he could skate fast, was all over the ice, he hit, he was involved in lots of scoring chances, he could shoot.
But, ultimately, his puck skills were not great, he was neither a great goal-scorer nor a great playmaker.
[Nice play by McDavid on the 4th goal as I write this].