^^ It is absolutely possible, in fact guaranteed, that Sami would be worse than Umar. I would prefer Pakistan to play with 10 players rather than include Sami in the team. The way he bowls, he not only gives away runs, but releases pressure that's built up from the other end, and has a negative effect on his own teammates and completely demoralizes them. It's like the other team is playing with 12 players. So I'd much rather have a competition between Pak 10 vs Opposition 11 (without Sami) than between Pak 10 vs Opposition 12 (with Sami).
Just watch the first Test Sami plays and you'll see what I mean.
If you add Imran Farhat to the mix of the starting eleven Pakistani team with Sami, that makes it 13 Aussies vs 9 Pakistani :-).