Reason for optimism: Thanks to the removal of below-below-replacement performers in the rotation, there's going to be a big improvement in runs allowed.
Reason for pessimism: If Mike Trout plays at the level of merely a 7.0 WAR superstar, there's probably little chance the Angels can play .500 ball.
In 2015, the Angels weren't nearly as good as their final record, as the foundation for their 85 wins that year was built on the unlikely feat of finishing 18 games over .500 in one-run contests. That's almost never a persistent trait (Texas Rangers fans, consult your preview) and, sure enough, the Angels went 17-20 last year in such close affairs en route to winning just 74 games -- their worst season in the Mike Scioscia era, which began in 2000.
Sabermetric principles tell us a team made up entirely of replacement players would win about 50 games in a season, so 74 wins is a pretty disappointing result for a team which annually gets about 10 WAR from one player -- Mike Trout.