I think one of the only strategies left today (assuming the serve and groundies have still allowed the 1% to happen) is whether/when to come to the net or not.
It is interesting that people say how long the rallies have become with the slower courts. Sometimes I have rewound my DVR trying hard to find the last forehand or backhand they hit, and I have to go back many points. Commentators applaud 25 shot rallies, but we forget how many points ended with a service ace, or a weakly returned serve and put away, or an unreturnable groundie. Add in the unforced errors which are a result of mental impatience/exhaustion/boredom, then not that many strategy opportunities left. Unless just being focused on every point (like Nadal) is a strategy (I don't think so).