Well, twslam07, you completely lost me at 2 and 3...
Getting Teague as starter PG instead of Rondo?
Getting Ariza intead of Casspi? (No, wait - instead of Casspi & Gay together??)
You are off in so many ways, IMHO, that you got to be joking...
The idea is about fit. Do you believe Teague is a better fit with Cousins than Rondo is with Cousins? It's up for debate. If Rondo can continue to knock down threes at this rate, I think I would rather have Rondo. If Rondo can hit threes and play defense like he did last night, I know I would rather have Rondo.
If you're going to play a non-shooter next to Cousins in Cauley-Stein, having 3pt shooters at PG, SG, & SF is very important for a dominant big like Cousins. Rondo has never been a good shooter up until now. Has he finally figured out his shot? Maybe, but Teague is a much more proven shooter who we know we can rely on to knock down shots year-in, year-out. In addition, Rondo is more of a catch and shoot player (who has a slower release) whereas Teague can pull up off the dribble and around screens. This would make a pick and roll game between Cousins and Teague more difficult to guard than a Cousins and Rondo pick and roll.
Teague also has been a better defender than Rondo over the past couple of seasons. Showing me opponents 3pt% isn't going to convince me otherwise (especially when you're showing it for PGs). You mention our 3pt defense and that usually starts with the PG. Allowing penetration and forcing our team to collapse (thus leaving open 3s) is a big problem. Having a quicker guard who does a better job at staying in front of his man would help out with that. If we're going to have good defenders at SG, SF, PF, & C, I can live with Rondo's defense, but if our team is going to move forward with average defenders like McLemore & Gay in the lineup, our upside as a team is going to be capped.
You mentioned would I rather have a distributor or a scorer when talking about Teague & Rondo. I would reply that you can't put Teague into one category. He's a better scorer, shooter, & defender than Rondo. Rondo is a better passer, game manager, & rebounder. If your other starters next to Cousins are Lee, Ariza, & Gibson, you need to have a secondary scorer out there to help relieve the pressure. If you have Teague, Gay, & Cousins, you might run into problems. Again, it's about balance and fit.
As for the Casspi vs. Ariza debate, I'm surprised that you're seriously trying to say that Casspi is a better defender than Ariza. I mean really? Ariza has been consistently one of the better perimeter defenders in the league. The last game against Indiana, we had Casspi defending Paul George (Gay was sitting out of this game) and he was getting lit up. He had no chance at stopping him. Did Casspi remain in the game considering he was our best defensive option? No. We ended up putting a 6'6" SG (Anderson) on the 6'9" Paul George to try and slow him down instead. Are you going to sit there and say that at least any team in the NBA...ANY TEAM...would have benched Ariza in favor of James D-League Anderson to try and slow down George? Good luck with that.
As for the salaries, yes, Casspi is on a great deal and gives us a lot of production which makes him a valuable player & trade asset. However, I don't see him as a starter on a contending team. His defense, decision making, and turnovers make him an unattractive starting option (love him off the bench though). In my mind, if a player is not a star/franchise player, they need to be a good defender to help maximize the potential of your starting lineup. Casspi doesn't fit that mold and Ariza does. Besides, Ariza's contract is very good as well and it's one year longer than Casspi's meaning that we will have more cap space to work with in the following season as Casspi will likely make more than $7.4 mil in 2017.
Literally, everyone is a good defender on the roster I put together, and everyone (except Cauley-Stein) is a good shooter. Cousins & Teague are the scorers in the starting unit with Lee, Ariza, & Gibson able to punish collapsing defenses with their shooting. Then you have Clarkson & Bazemore to give you a scoring punch off the bench. You can never have enough defense & shooting especially around a big like Cousins and that's exactly what the roster I made gives us.