Sure, there are examples of clubs taking a while to settle into new stadiums. But Spurs ought to be more immune in that respect than most - for the simple reason that they aren't moving directly from their beloved, intimate, atmospheric, old home to a bigger, soulless new stadium on an anonymous, new site. They are, instead, moving directly from a cavernous, soulless, neutral stadium into a far more intimate stadium on almost exactly the same site as their old stadium.
As to the integrity of the competition, as I said, there are surely other factors that are far more likely to have a direct effect. Certain clubs that can afford to do so stockpile players and then loan them out to other clubs in the same league. Those players, quite often among the best players at their loan clubs, get to play against all teams in that league other than their parent club. Fair? Right? Or how about fixture scheduling? When Spurs were chasing Leicester a few years ago, they played after Leicester for something like six weeks in a row. Consequently, they were always having to claw back the gap from 8 points to 5 points. And that takes a toll. They were never given the opportunity to play before Leicester and reduce the gap to 2 points. We'll never know whether that might have made a difference.
As to Spurs using Mace as an excuse, it's not an excuse; it's a fact! Imagine if Manchester City were due to play a Champions League semi final against, say, Shakhtar Donetsk and the day before the game, the UK's air traffic control systems went down, grounding all flights to and from the UK. City wouldn't have time to get to Donetsk by other means so would be unable to fulfil the fixture. Would you say that it was fair and reasonable for the result to be declared a 3-0 win for Shakhtar? That blaming whoever was charged with maintaining air traffic control systems was just an excuse? That City should have anticipated that such a thing could happen and travelled a day earlier?