Doc probably convinced Danny that he didn't need a big because he can win it all with Small Ball.
Of course this is just pure speculation.
But I feel like that conversation went down like this.
Danny: Hey Doc we've got a chance to get Kenyon Martin and Chris Andersen. What do you think?
Doc: Who?
Danny: K-Mart and the Birdman!
Doc: Walmart and Larry Bird?
Danny: No, No, Kenyo...
Doc: I only like guards, we're gonna win with small ball. Trust me, I'm Terrific.
Danny: Are you sure?
Doc: How dare you question my coaching? I'm the best coach in the league!
Danny: I'm just...
Doc: SHUT UP! To prove you wrong, get me some guys from China, I'd make them look like all stars.
Danny: Okay, I guess...