He had no instructor. Efren has this thing, he doesn't go to a maestro who can't beat him . I've seen his scoff instructors at Hard Times. One was trying to convince him he was drawing the cue ball wrong. Someone who he could have given the 6-out.Efren was so good before he came to America, that he had to quit playing for 5 years for lack of opponents! Can you imagine someone so good they couldn't get action in the Phillipines?Not only that, but he dominated in Balkline Billiards as well! Now, I'm no Billiards expert, but it's simply mindblowing that someone can play as controlled of a game as Balkline with that kind of stroke!
Playing on Simonis and proper, dry conditions eliminated the need for some of the power, so he changed his stroke up. I don't know if he got instruction or not, but he's such an intelligent player that I'm sure he picked up a lot just from watching others. A player of that caliber cannot trust his stroke to just anyone...
Anyhow, if you watch the old greats, they all have very ideosyncratic styles. This could be because of the lack of instructional material at the time, but I believe that the equipment is a major factor. It is extremely difficult to play well on slow conditions with a snooker stroke. Even the old snooker greats dropped their elbows etc, because the cloth was much slower and they didn't have steel backed cushions or heated slates. Diamond tables have completely changed the way the game is being played, as has Simonis cloth. I think, not necessarily for the better. Sure people pot more accurately now (at least some), but we have lost the unique strokes that were needed to get out when the rack was tough. Now you can go four rails without even touching the ball. Oh, well.
He also has changed cue specs . He no longer plays with really long and heavy cues . 59", 19 oz is fine now .
He used to wrist the cue a ton. Not anymore.