Alabama, Clemson top future defense power rankings

Spring practice is all about the future, so let's look ahead again -- way, way, ahead.

It's time for the third installment of ESPN's future power rankings, which examine the next three seasons: 2017, 2018 and 2019. You've already seen rankings for quarterbacks and overall offenses). The defenses are up next.

These rankings consider current personnel, incoming recruits and each unit's recent trajectory. Insider solicited input from approximately 15 coaches, as well as ESPN recruiting, to craft the Top 25.

Here are the teams with the best outlooks on defense through 2019: