You have to be careful who you learn it form -- DeMarcus was playing PF for us the entire second half of the year. Ther key factor there was Dalembert. Cousins DOES have the offensive game to play PF. He has the offensive game in fact to likely dominate at PF. And when he's there you are just overwhelming with size/rebounding. Its a huge edge to be able to twin tower somebody. But the key guy is Dalembert, because he's a center who can anchor the middle defenisvely, but who also has the athleticism and mobility to take those tough PF matchups instead of Cousins.
On offense, there is no problem. Cousins can play PF or C on offense, and yes, there is some Webb to his game. As a rebounder Cousins can play PF or C. The difficulty is on defense. Therefore what you need from a person paired with Cousins is:
1) a shotblocker able to anchor your interior defense, ala Noah, Chandler, Ibaka/Perkins etc. (it ain't coincidence all the remmainging teams have them)
2) a mobile defender able to guard more mobile PFs that COusins doesn't matchup well with
With Dalembert, you have both of those areas covered. He's a rare player in that. Chandler is a free agent and could do both of those as well. But few players can do both. There are big cetners who cna do #1 but not #2. there are PFs who can do #2 but not #1. But we already have/had one of the rare guys who can do both #1 and #2.
Biyombo is only listed at 6'9". We'd be getting a lot smaller. Basically unless he is actually able at that size to shut down the middle ala a Dalembert, you are losing in the deal if that's the swap.