People tend to forget that Bednar is already 30 and last season looked toast. Granted, he's bounced back big this season so that's a plus, but couldn't care about how much control a 30+ year old reliever has left. He is only under control for one more season anyways, so not crazy about giving up a top guy like Nimmala + more to get Bednar included in a deal.
As for Keller, he has control for three more seasons and Atkins historically has liked trading for players with control. $16.9M in 2026, $18.4M in 2027 and $20.4M in 2028, which is quite reasonable if he continues to post 2-3 WAR seasons. Pirates might want to rid themselves of that contract anyways, so who knows what they ask for.
Keller is a solid arm, but he's no different than what the Jays have right now IMO with Berrios, Gausman and Bassitt. He's a solid mid-rotation arm and in essence replaces Bassitt for next season. As well, Jays would save money with Keller since signing a similar starter likely would be around $20M+ AAV per season.
You can never have enough pitching especially down the stretch, so Keller would be a nice addition. Not an ace by any means, though he could start a Postseason game for sure and maybe Pete Walker could untap some more potential from him.