Plastic'll do that you you. Every league has that one team that's either new or acts like it, throwing plastic straight down the middle. We've got one (to be fair, one guy has a Big One, though I don't know why, and another has what looks like an old 80-grit black urethane ball). They're frustrating, both because they completely destroy any semblance of an oil pattern and because, coupled with that, one of them will get on a tear for at least two or three frames, giving them an easy win.
There's not much you can do about it. It's the worst kind of carrydown, and it basically turns the lanes into 50+ feet of medium to medium-light oil. Conventional light-oil wisdom is long-and-sharp ball reactions (look at balls like the Power Groove, Tropical, Punisher) and that definitely doesn't apply. You need a dull, even ball to have any hopes of picking up a decent roll, but you'll never find a factory ball with a surface like that for lighter oil.
Maybe a milder, matte solid reactive would work. The now-discontinued PG solid/sanded (not the black one, though) might work. A Hot Wire might work. Or play their game: chuck it up the middle and hope for the best.
Sorry to hear that your average dropped like that. Seven pins in one night. Dang.
SH