is monica already using an oversize like 107-something? i thought she was using 102-105. but it was already kinda big for that time because majority of players were still using 95 or smaller.
what i gather most from watching old seles matches was that she was not as one-dimensional as i remember her to be. she mixed up her angles. she especially loved targeting the side T's. she also hit some heavy topspin loopers to break up the rhythm. she used all of this to set up her flat drives to the corners.
graf was always playing catch up in this match. i think she just didn't execute as consistently as she needed to. i remember it was her unforced error count from her forehand that told the main story of this match.
She did have decent variety. She played short angles, she sliced, a few loopers (as you mentioned), she hit various spins, and, of course, those flat slapshot winners. And, pre-comeback she was very good defensively.
Like you, I always remember Seles being more one dimensional - the flat, hard winners down the line or angled cross court. But, she played a lot of positioning rally shots with more margin and less speed (though still pretty powerful) than her flat winners. I noticed a lot of times she's get pulled wide to what would have been her forehand (ad court), and she'd hit a looping cross court deep forehand to recover. And, she loved hitting medium paced rollers into the forecourt in order to open up the court.
What I remember correctly is that she had horrible net instincts. Weird, she had no problems taking groundstrokes out of the air if she got caught mid-court, and she'd swing volley a few times when actually at the net. But, she retreated so much. There was one point where she had to come and take a ball in the service box, she crushed it but Graf got it back, If she just would have closed to the net, any sort of volley, no matter how ugly, would have been fine, but she retreated and missed the ball coming back at her, which she was hitting from her shoe laces near the service line as she's moving backward.
I thought this was a high quality match despite Graf's 66 UEs (as Moose pointed out). She wasn't missing because she was necessarily "off" or tired. She knew what she was up against and at times was just pressing, trying to hit closer to the lines or deeper than maybe she normally would as to prevent Seles' attack.