There's a bunch of factors, but the tombstone drop was probably the largest issue.
The move itself was essentially MK9 Jax's EX ground pound that was sped up to well over twice as fast. If that wasn't bad enough, there was a glitch where sidestepping would remove the cooldown on TSD instantly, basically making it possible to just do it over and over. Only way to avoid it was to jump...which got beat by his projectile due to the shitty jump heights. He also possessed one of the best stances in the game (very safe), as well as a teleport that, when the full animation landed, led to free TSDs, among other situations.
He probably won every matchup at least 7-3 in his favor. I'm not a big MKD guy, so I wouldn't know too much of all the specifics. @
General M2Dave was the TSD Master of the day lol.
MKA's Dairou was severely toned down, though...partially due to TSD actually getting a huge nerf (roughly 3 second cooldown and no-blocking period, glitch fixed, slowed down), but also because of new things introduced (jump height increased so iron leg can be avoided by jumps, divekicks exist now, new characters that took advantage of all the changes and beat him as a result, etc).