Nyorai kuenderera mberi kweiyi ndima - Mumwaka wa2015 / 16, Cowen akarwira kuti azvisimbise mukati meOttawa lineup, dzimwe nguva achizviona semunhu ane hutano. Musi waFebruary 9, 2016, Cowen akaverengerwa mune blockbuster, vatambi vapfumbamwe vekutengeserana neToronto Maple Leafs. Cowen, Colin Greening, Milan Michalek, Tobias Lindberg uye Ottawa's 2017
vakasarudzwa mumutambo wechipiri vakatumirwa kuToronto mukutsinhana nekaputeni weMaple Leafs Dion Phaneuf, Matt Frattin, Casey Bailey, Ryan Rupert naCody Donaghey. Musi waFebruary 26, 2016, Cowen akaiswa pakuregererwa neMaple Leafs uye akazoendeswa kune yavo AHL mubatanidzwa, iyo Toronto Marlies. Cowen akabva atumirwa kumba neToronto kuti amirire kutenga uye kupihwa rusununguko rwekutaurirana nemamwe matimu nezve chibvumirano chitsva chemwaka wa2016 / 17; kutenga-chibvumirano chaCowen kwaizopa maLeafs ne $ 650,000 mubhadharo wekukweretesa chikwereti chemwaka wa2016 / 17.