But leaving diplomacy out of the question is like leaving it out of the game. Strong diplomacy (and the game is *called* Diplomacy after all) can get both that strategic mind and the tactical mind on your side.
But if we must leave it out... Strategy is long term, and without it you will be constantly putting out fires but not have any direction. Tactics can handle situations, but are limited in what you can do by the moves available and will never, by themselves, see you to the end game. With good diplomacy, tactics can get you to the middle game, but then even the diplomacy becomes less important on some scale as the remaining 4 or 5 players theoretically all have the size and diplomatic skills not to fall for the ploys and traps, so long term strategy becomes important and relaying that to others in opemn and honest diplomacy becomes the key to seeing your strategies through. One in the end game, it goes back to tactics. With just three players, the tactical mind is the one that can break the line because there is no mor elong term and there is no tricks you can do to equally skilled opponents diplomtaically. And with three left, if one person tries to get ahead, the other two will always push him back down if they can, so the tactical mind will see what is coming from the other two and have the best shot at breaking through.