Until few years ago, players had real weapons and also weakness -- take champs from last gen..
(Rog is exception here.. considering him from the last gen)
Pete: weapon-serve, fh / weakness-bh
Andre: weapon-fh, bh / weakness-serve
Rog: weapon-serve, fh / weakness-bh
But as we get to the next gen (Nadal, Novak, Murray... plus other top pros), we seen a major change in that dynamic...
that strength/weakness gap is getting thinner and thinner.. they're well rounded.
Can we say that strategy* is.. having a plan (tactics) to
1. playing to your opponent weakness
2. force your opponent play to your strength
Now, with players having very little weakness, how can one have a set strategy?
So, IMO this old definition of strategy is changing (evolving)....
Fitness "be really fit to outlast your opponent" is part of new strategy.
There will still be the classic strategy* (as defined above).. but it is used a little against non top players who still have some weakness.
But against the top players, it is replaced with a new type of strategy..
which is very dynamic one which has many mini strategies depending on the situations (or how the opponent is playing that day)