First, one has to define a boomerang team. The concept is not hard to articulate: A boomerang team enjoys noticeably good fortune in one season. The laws of averages suggest a lot less good fortune the next season.
A classic case of the boomerang effect in college football was the University of Arizona in 2014 and 2015.
The 2014 Wildcats made a New Year's Six bowl. They were a very good team. They deserved to be where they were, in the Fiesta Bowl against Boise State. That they -- or any team in a given season -- got lucky does not detract from their achievements. College football and all sports involve a certain degree of luck. Successful teams aren't (generally) luck-free; they merely make the most of luck when it comes.
Arizona did that in the 2014 regular season.
The Wildcats used a 36-point fourth quarter capped by a Hail Mary to beat California. They trailed Washington in the final minutes and did not have the ball. Washington, however, fumbled in an attempt to run out the clock. Arizona recovered and later kicked a winning field goal. Those two wins enabled Rich Rodriguez's group to win the Pac-12 South Division title and crack the NY6.
The accomplishment mattered, but it remained hard to expect Arizona to get that same level of pigskin providence in 2015.
Sure enough, that U of A team went 6-6 in the regular season. One year's Fiesta Bowl was followed by the next year's New Mexico Bowl. Regression was a beast, as it often is for so many teams which catch all the right bounces in a given season.
Much as the Oakland Athletics and Colorado Rockies are winning tons of close games right now in Major League Baseball -- but will find it hard to replicate this success in future seasons -- college football programs can't depend on the right bounce of the ball in consecutive years. To be more precise, programs can't play in loads of close games in back-to-back years and count on the idea that they will always pull through. Highly successful programs will win enough close games to matter, but they turn the laws of averages in their favor by winning more blowout games so that their close shaves aren't as numerous.
Arizona wasn't good enough to beat opponents by large margins in 2015, so in the absence of the manna from heaven it received in 2014, the Wildcats were in deep trouble.
The boomerang flew back in Arizona's face and whacked the Wildcats.
So, where is the best Power 5 conference boomerang candidate for 2018? Look to Miami.
The 2017 season wasn't just "The Year Of The Turnover Chain" in South Florida. Miami reveled in a tidal wave of takeaways, yes, but there was a bang-bang call at the 1-yard line against Florida State which went the Canes' way. Miami benefited from an improbable fourth-down completion against Georgia Tech, en route to a narrow, last-gasp win.
Much like 2014 Arizona, 2017 Miami was a very good team. The Hurricanes knew they had to be better to take down Florida State and cross the thresholds previous UM teams -- under Al Golden and Randy Shannon -- were unable to successfully navigate. The program did make a "U Turn" under Mark Richt. The improvement in coaching, which translated into better handling of difficult situations, was noticeable. Miami earned what it received, a trip to the Orange Bowl game against Wisconsin.
Nevertheless, while acknowledging that Miami earned everything it attained last season, the ball nevertheless bounced in The U's direction a lot.
The ACC Coastal Division doesn't appear to have any heavyweight team this year -- Virginia Tech isn't at its zenith, Georgia Tech's defense faces ample questions, and the four other programs in the division all have enormous obstacles to confront. If you wanted to say that Miami is still the class of the division, you would probably be right.
The point of emphasis: The division will likely be decided not by how high Virginia Tech or Georgia Tech rise, since the ceilings for those two teams appear to be lower than in recent years. The ACC Coastal will probably be decided by how far Miami falls. If the Canes are only one or two games worse than in 2017, they should retain the division title. If they regress by three or four games, one of the "Techs" can sneak in and go to Charlotte to play (let's face it) Clemson.
The lesson for Miami, if it wants to avoid the fate of other boomerang teams such as Arizona: Be a touchdown better than last season, so that if the ball bounces in the wrong direction, the difference won't mean a shift from a three-point lead to a four-point deficit, but from a 10-point lead to a field-goal advantage.
Can the Hurricanes stay ahead of the smaller margins likely to greet them in 2018? That is the foremost question to ask before the ACC Coastal race begins.