DE and BIG DMD Sega playfields tend to be very robust in my experience. They tend to clean up literally to brand new with some elbow grease and novus.
You don't really see many worn-to-wood spots on DE/SEGA games, other than typically around scoops, or well used examples where a ball is constantly kicked out in the same spot (GNR, LAH)
Based on the lack of wear at the shark hole, I'd wager this is a relatively low play machine compared to others. As an aside I would guess MOST Baywatch's PROBABLY were less played compared to their peers, as I can't really imagine walking into an arcade as a pubescent teenager when these were on location, and pumping quarters into this over a slew of other flashy, B/W titles, or more masculine themed games.
Nowadays, as a discriminating connoisseur who values play over theme, it's a GREAT game. And the theme now kind of just kind of works as a generic beach theme, or 90's nostalgic cheese, in a good way.
Congrats on the pickup!