I call BS on all this talk of benching Hazard and Diego being part of some sort of tactical master plan.
There was no change in how Chelsea played (was the same formation) or any particular frailty in spurs that were exposed. Batshuayi for Costa, and Willian for Hazard only weakened the team as they were like for like substitutes of lesser quality. For most of the game, Chelsea were the weaker team and were lucky to get 2 goals from set pieces against the run of play. There is no evidence of any tactical nous.
My suspicion is that Conte wanted to avoid the potential psychological pressure of losing to Spurs at full strength (which would give the momentum to Spurs for the PL run in) and thus decided to rest the two players. If Chelsea lost, he would have explained it away as Chelsea not being keen on the FA, with talks of "a full strength Chelsea would have won" (and if they won - we can all see the thought plan). If Spurs had dominated them effectively earlier in the game e.g. leading 2-0, I doubt he would have brought on Hazard or Costa.
All this talk, after the fact, is simply trying to make himself look better tactically, and improve his image which was in shambles after he looked clueless at old trafford.
EDIT: The 3-man back deployed by Poch and the man-marking used by Mou were two actual tactical changes that were made by those teams for use against Chelsea.