Those things happen. Every single team, contender, cup winners, have games they blow leads or play like dog shit or lose to tanking teams. No team goes 82-0 and no team only loses games to contenders.
What I want to see is just consistency. If in March we are sharing around how the Leafs have the worst record in the league against the bottom 5 teams again then Berube has failed IMO. They will lose some of those games, but each game should look close to the last until we know what we get out of them each night.
Then when those big moments come, they are so used to going 100% day in and out when they can give just a tiny bit more they will do special things.