IMHO, after last year's playoff loss, Woodcroft tried to change things to create a better team for the playoffs, including trying to go to the Boston/Vegas zone defense, as the Oilers' man defense had been rather easily exploited. This required that everybody play tough defense and not cheat for the break as they could often do playing a man defense. Woodcroft's problem was (1) he really didn't have the quality of defensive personnel to run this zone defense properly, and (2) there didn't seem to be much team buy-in. So, Woodcroft's attempted changes were a disaster all around, compounded by the McDavid injury.
Knoblauch then comes in, McDavid gets healthy, and the Oilers go back to their familiar and comfortable formula for last season and take off again in a way that will probably get them into the playoffs. The thing is that style of play works great in the regular season, and of course the Oilers have to make the playoffs or nothing they do really matters, but whether it will bring them deep success in the playoffs is another question since so far that system has come up short for them. If it doesn't work for the Oilers again this playoffs, it will be interesting to see next season if Knoblauch then tries to make basically the same changes that Woodcroft thought needed to be made.