On defense, the Leafs not only lacked right-handed options – Timothy Liljegren was their only regular right shot – but they lacked quality, top-end players. Related to personnel issues on defense, Toronto’s penalty kill has been an Achilles heel all season. They currently possess the worst penalty-kill ranking of any team in a playoff spot.
Every team can always benefit from additional quality on their team – look at Vegas acquiring Noah Hanifin even though they returned their Cup-winning defense from last season – but in terms of the holes that absolutely needed to be addressed in some capacity by Brad Treliving, the defense and the PK were the top two, especially for a team lacking in draft capital and hesitant to trade its top prospects.