Is anyone actively trying to grind for the Buxton (Legacy Collection)

With all the all-star content, I've been grinding a lot the last few days. I know I'd probably get the Buxton eventually (as long as I don't stop using the all-star cards) but I was wondering if anyone is actively trying to grind for it and if so what methods?

I suck at the game but was curious so I tested it. I did play vs CPU on GOAT and lost a game 5-2 but got around 6000 PXP towards Buxton. Likewise, I played on Rookie and scored around 20 and got 3000 PXP.

What's your preferred method for maximizing the PXP?