When Jimmy Johnson came to Dallas he already had Michael Irvin on the roster and the first overall pick with Aikman sitting there. Anyone would have taken Troy. Johnson had little or nothing to do with bringing either one of them to Dallas.
Then, the next year, he tried to draft two defensive players before finally settling on Emmitt Smith.
What if Landry would have drafted someone other than Irving in his last draft?
What if Landry would have won the final game of 1988 against Green Bay and Jimmy would have walked in to the 2nd overall pick instead of the 1st? It was a close game and whoever lost got first overall. Dallas would have taken Tony Mandarich. They briefly thought about it even with the first overall but Troy was just too good a prospect.
What if Jimmy's attempted trade up for Ray Agnew would have worked? What if his attempted trade up for James Francis would have been accepted? Either one would have seen Emmitt in another uniform. It was blind luck that he ended up in Dallas.
If those things (that were very close to happening) would have happened, Jimmy wouldn't have been coaching Troy, Emmitt, or Michael and history would likely be way different.
The bottom line is that the triplets were what drove those super bowls and Johnson was only responsible for getting one of them in Dallas (Emmitt) and he tried like hell to draft someone else first.
Really good coach but had some luck on his side and wasn't the draft guru people made him out to be.