They're still the smartest pitching team around but the gap between them an other teams has shrunk significantly. It used to be
Rays>>Dodgers and Guardians >>>>>>Rest of the league
Now it's more like
Rays >Dodgers, Guardians, Mariners >Cubs, Brewers, Phillies > Rest of the league
Specifically to this rumor though, I don't think there's much to fix with Assad. He was pretty great from June on. Wesneski had his issues with lefties, though they're not very different from Alzolay's early in his career so I'm not convinced the Cubs can't fix him if he sticks around.