Your first sentence says it all. "To round out the roster and make us more competitive" NOW! That was the shocker as far as I was concerned. Not only does it not reduce our roster (adds to it), no draft capital, and it's another 30+ year old player. Hard to fathom on so many levels.
But as you said, it does improve our team, both from a financial perspective and on the court as well I believe. Olynyk has an incredible Basketball IQ and between his time in Boston and Miami played some really big and important minutes in Big games. Is he better than Bogey? I think not. It's kind of apples and oranges with a little overlap. Careerwise, Bogey is the better shooter, Olynyk the better rebounder and assists, not sure about D, though Olynyk gets more blocks. But Olynyk is not the only one we traded for.
This kid Saben Lee is a player and has been tearing it up in G League particularly. People have been wondering about a Backup PG for the day that Conley is gone which is inevitable and this is our guy. Lee has been stuck behind two lottery picks in Cade Cunningham and Killian Hayes. This guy is only 23 years old and much more than a throw in IMO. With the dubious win/loss metrics from Sexton and questions concerning his ability to play team ball, Saben Lee is the insurance policy we've been looking for IMO.