Then they ran into a Royals team on a high from an improbable comeback in the AL Wild Card Game, lost back-to-back extra-inning games at home and ultimately got swept in the AL Division Series.
Some believe clinching early may have hurt them.
"Tip your hat to the KC pitching -- they were spectacular -- but we weren't ourselves," Angels catcher Chris Iannetta said. "That momentum can definitely help. It's definitely beneficial."
An Angels playoff appearance in 2015 will likely follow their best baseball of the season and basically an entire month of close, do-or-die games. It's exhaustive, taxing, but there's a segment in their clubhouse that buys into the belief that those close games at the end readies a team going into the postseason, especially the first round.
"You want to be hot going in," Angels right fielder Kole Calhoun said. "We're definitely playing good baseball, and if we do get in, we have a confident bunch of guys in here right now. Hopefully that can carry over."
Many will argue that momentum is non-existent in baseball, even in the postseason. In fact, none of the 23 teams that posted a .700-plus winning percentage after Sept. 1 since 1995 have gone on to win the World Series.
But six of the last 20 World Series champs were Wild Card teams, clubs that, in theory, would be finishing their regular seasons with intense games. A Wild Card team won the World Series from 2002-04 and appeared in the Fall Classic every season from 2002-07.
Iannetta's 2007 Rockies won 14 of their last 15 regular-season games and then seven straight in the postseason, until being swept by the Red Sox in the World Series. And the 2014 Royals team Johnny Giavotella was part of -- but not on the postseason roster -- came from behind in the AL Wild Card Game and finished 90 feet away from a World Series title.
"The more pressure-packed games you play, I think it can prepare you for the actual playoffs themselves, especially getting hot at the right time," Giavotella said. "We're doing that. "
Momentum may in fact be a myth, but maybe there's something to be said for playing all these meaningful games going into the playoffs.
The Angels just hope they have a chance to find out.
"I think the blueprint, if there is one, is to get hot first and foremost at the end of the year, and then you have to find a way to sustain it and maintain that," Iannetta said. "And I think the only way to do that is to keep playing."