The Tigers have not won a Championship game since New Year's Day and although they did a good job of restricting the Whites in the first half at the KCOM Stadium, they were unable to live with them over 90 minutes.
A 4-0 win reflected the contrasting fortunes and confidence of both sides at the moment.
When Luke Ayling put Leeds in front with a deflected shot after six minutes and Pablo Hernandez hit the crossbar two minutes later, a comfortable away win looked on the cards, but it was not forthcoming until late in the game.
“The early goal knocked us,” admitted coach McCann. “But apart from Hernandez's shot hitting the crossbar there was very little in it in the first half.
“Even the first goal was a deflection. That's just the way it's going for us at the minute.
“The second goal (scored by Hernandez shortly after the break) has thrown it up in the air.”
Some good goalkeeping from captain George Long meant Leeds did not pull away until substitute Tyler Roberts scored twice in the final 10 minutes. Although Nortbert Balogh hit the post with a brilliant turn and shot at 2-0, the scoreline was a fair reflection overall.
“Leeds are a very good team with serious energy and very good on transition,” said McCann.
“The last two goals were on transitions. We knew that was a big part of their plan but we just couldn't keep up with them.
“Leeds were good and they're a top team. There's little doubt they'll go up.”