When Air Force knocked off St. Cloud State 4-1 on Friday in the first semifinal of the NCAA West Regional hockey tournament at the Denny Sanford Premier Center, it marked the 13th consecutive year a No. 4-seeded team defeated a No. 1 seed.

Get used to it, Falcons coach Frank Serratore said.

“This is the world according to Frank, which can be a little bit whacked,’’ he said. “Every year you’re going to have six or seven teams that are just a cut above everybody else. Then you have six or seven teams that have fallen on hard times and they’re down here. Then you’ve got this huge middle where literally anybody can beat anybody.

“And when these guys play the elite six, the elite six better be hitting on all cylinders. If they don’t, you can have results like you did tonight.’’

Air Force, which advanced to the Northeast Regional final last year before falling 3-2 to Harvard, didn’t sneak up on St. Cloud State.

“That’s a great team. They weren’t taking us lightly, and they weren’t taking Ferris State lightly two years ago,’’ Serratore said. “That’s just the landscape of college hockey.’’

Etc.

• Friday marked the first time a Division I hockey game had been played in South Dakota. The locals are taking to it. “This is awesome. It’s a great level of hockey for South Dakota,’’ said Kip Harrington, who organized a group of eight recreational players in their 30s through 50s in Rapid City. The crew drove the 350 miles across the state on Friday to watch. “Hockey has really taken off, especially in Rapid City and Sioux Falls.’’

• The regional’s host, North Dakota, did not make the NCAA tournament field, but there was a strong green presence in the stands. That was evidenced at the end of the national anthem, when the UND fans sang, “and the home of the SIOUX!’’