How can 2015 and 2017 show the Importance of Turnout in Outcomes of Elections?

-2015 saw Higher Turnout from Disillusioned Conservatives who 'came back home' after Fears of a Coalition of Chaos with Labour and the SNP -2017 saw the 'youthquake' as Turnout there Increased due to Corbyn's Leadership. This helped the Gap in Labour and the Conservatives which may be why Theresa May never got her Majority