To make my stance clear, I don't think Dirk is the #2 PF of all time, and I don't think he is definitively better than Garnett.
However, if I was to build a team, and I have a choice of Dirk and Garnett as my #1 franchise guy, and I cannot flip a coin to decide who to pick, I will pick Dirk, because I feel it is easier to build around Dirk than it is to build around Garnett.
I think the #2 PF of all time is Barkley ... I think ... perhaps.
The only clear ranking of PF is that Duncan is #1.
Dirk/Garnett/Barkley/McHale belongs to the next group.