One thing that might be really interesting is when draining from the ring, you get the 10-second 'out of ring' countdown from the ref while you try to get back into the fight. This would allow them to get pretty aggressive with killing one or both bumper flippers in response to enemy attacks or some sort of timer, but keeping the mini playfield progress in play while bashing the lower playfield, maybe even gaining some multipliers or "steel chair" power ups or something to take back into the ring?
That leads to thinking about intentionally draining off the upper PF as a valid risk/reward strategy where the lower PF could be used during a 'match' to significantly increase the scoring or progress on the upper PF during a match, but stay out too long and you are DQ'd...
Just spitballing...