Burns a year of his ELC. Already played in 6.
It's funny, I know conventional wisdom says you should avoid burning off a year of an ELC in these situations. But imagine if the Leafs gave Nylander and Marner 10 games in the first year of their ELCs before sending them back to the OHL/AHL instead of having both of them see their first year slide. Imagine they both negotiated their 2nd contracts a year earlier in their careers. Hindsight is 20/20 and I don't recall anybody suggesting the Leafs do this, but there's a pretty darn good chance our cap situation would look a heck of a lot different than it does today if that happened.
In Marner's case, a year earlier would have made a big difference- BUT- that year where he wouldn't be on his ELC and would be in the first year of his deal would have meant not icing as strong a group. The fact that we didn't get past the first round anyways probably means in hindsight who cares, but at the time everyone would have been upset we didn't have Marner on his ELC for an additional year. We may not have been able to sign Tavares.
In Nylander's case, I highly doubt we would have burned two years of his ELC for 10 game and 22 game seasons. If he had only had one full season, there is very little chance we'd see a long term deal, he would have been bridged because we didn't know what we had, and we'd probably be coming to the end of that bridge deal this season and probably be paying more for him starting next season.