There was a time when The Undertaker and good matches didn't go hand in hand. During the character's early days it was much more common to see slow, plodding bouts that focused on his zombie-like gimmick than ones you'd enjoy watching again. That all changed towards the end of the '90s.
Suddenly, 'Taker had a zippier feel to his in-ring work. It also didn't hurt that WWE began booking him against guys like Bret Hart, Shawn Michaels, and Mick Foley, all of whom could bring out the best of the 'Deadman'. This was a huge improvement over the cluster of boring giants (King Kong Bundy, Giant Gonzalez, and their ilk) he had been expected to work with before.
As a result of being booked against better opponents, Undertaker could finally show how good a worker he was. That continued in more recent years, and the 'Phenom' arguably saved his best for what could be the final decade of his run.
Long live 'The Deadman'...
Steve Austin and The Undertaker never had the chemistry you'd expect from such a world-class pairing despite working together extensively. SummerSlam 1998's main event was a disappointment, and matches at In Your House: A Cold Day In Hell and Over The Edge 1999 were similarly flat.
Adding the Buried Alive gimmick to their feud in time for Rock Bottom in December '98 worked though. As over-the-top as the graveyard match is, Austin vs. Undertaker needed it to be exciting; again, other matches had been (and would be) awkward and disjointed, but there was no threat of that in a match type which allowed for brawling.
The match isn't perfect by any means, and yet it just sneaks into Undertaker's top 20 by virtue of being something different. It was also the best match he'd ever have with Austin, something that may come as a surprise for a duo that was consistently put together in major matches.