Haha, That's where I hit an ideological difference with most people. Would a player who is on an ATG level throughout a specific period be better than someone who manages the same results(over even better) by being so historically prolific(6 wpm for a fast bowler @18 per) for one half of the period despite being merely a good test bowler for the rest of the period? For me, not necessarily. For most people, Yes.
Ftr,
Waqar, 184 wickets in 31 games @ 6 wpm and 18.4 at a SR of 35.3, 89 wickets in 25 games @ 3.5 wpm @ 28.3 at a SR of 52.4
Ambrose, 159 wickets in 31 games @ 5.1 and 18.7 at a SR of 51.0, 150 wickets in 40 games @ 3.75 @ 21.6 at a SR of 53.5
Yes, Ambrose has a more rounded split but if Waqar managed to do something ridiculously impossible like maintaining a 6 wpm over a five year period for a fast bowler that despite him being merely good for the next five years, he can maintain a perfect record for the decade such as 270 wickets @ 5 wpm and an average of 21.7 with an unprecedented SR, It is to his credit, IMO and I don't think it's just that Waqar would be rated higher if he got 1.5 wpm less in the first part of his career and 1.5 more in teh second part.
Again, It's an ideological difference regarding how much value you give raw results and how much value you give splitting them evenly.