I guess your definition of straight isn't the same as mine. Just look at his follow through at 2:35 or 5:10
Certainly there are elements of Mizerak's technique not well-suited to snooker. He stands more upright, and as you've suggested the cue isn't always on-line after the shot is played. Alex Higgins' cue often finished in the light shade after he had hit the ball, and he jumped up on a lot of shots, but he had his chin lower to the cue than Mizerak and a very short backswing. Plus he learned the to play on snooker tables, which helps.
As Mizerak suggested in the post-match interview, he went on to play in at least two snooker World Championship qualifying events, that I'm aware of. In 1988 and 1989 he lost both of his opening matches 10-1 and 10-2 to Mark Rowing and Anthony Harris. In both he would have needed to win this first match, and then another four to get to the televised stages of the event, but the standard of the qualifiers was considerably lower then than now. Drop Steve Davis in that field and he would not lose too many frames in inevitably reaching round one.
Jim Rempe fared a little better, though. In 1987 he beat both Martin Smith and John Rea 10-9 to get to the third qualifying round, where he lost 10-4 to a 17-year-old Stephen Hendry. Hendry won his next match 10-7 to get to the first round, where he lost to Willie Thorne. In 1988 Rempe lost in the first qualifying round 10-4 to Jim Meadowcroft, and lost 10-5 at the same stage the following year to Bill Oliver.
Of the two it seems Rempe was the more capable snooker player, and from what I've seen had more of a snooker style than Mizerak.
