In the 13 games he was here Townsend recorded 4 goals and 2 assists. Across a season that's just under 12 goals and 6 assists. Ritchie this year in the PL with 35 games recorded 3 goals and 5 assists. Admittedly, he probably would've had more of each with the bad luck of the few times he's hit the frame of the goal and our strikers being donkeys when the ball is presented on a plate. Still, I'd probably go with the view that under Rafa, Townsend is probably a bit of an upgrade.
I'm not denying he had a good spell here, but it was only for not even half a season, he fucked off as soon as he got the chance and then reverted back to his usual self when moving to Palace. I don't doubt Rafa couldn't get the best out of him, but I don't see him as an upgrade when you consider the wider impact to the team.