What happened to the Ottawa Senators?

Nothing could stop the 2012-13 Ottawa Senators. They lost Erik Karlsson for most of the year. They lost Jason Spezza. They lost Milan Michalek. They lost Craig Anderson. And yet, the club continued to win, sneak inexplicably into the playoffs, and once again validating the theory that head-scratching success is the key to a Jack Adams Award.

But a year later, it would appear that we've discovered the one thing that could derail last year's Ottawa Senators: time. Specifically, a summer's worth.

Somewhere between the end of last season and the beginning of this one, the Senators changed. This year's team is a shadow of that team, all questions marks and holes. On Saturday, the club, desperate for points, gave one away to the Montreal Canadiens, squandering a three-goal lead with four minutes to go before losing 5-4 a minute into overtime.

Last year's Senators were the stingiest team in the Eastern Conference. It wasn't uncommon for them to go several games before surrendering five goals against in total. They surrendered 5 goals in a game just twice. This year, it's happened twice versus Montreal alone.

It happened twice in October, in back-to-back games. They did it 3 more times in November, thrice in December, twice in January, and 3 times in the 6 games they played in February. Not counting shootout losses, Saturday night in Montreal was the fifteenth time this season the Senators have surrendered five goals.

You can point to the loss of Daniel Alfredsson and the composure he brought to the lineup all you like, but no one man can have that kind of impact on a goals against average unless he plays in net. The Senators' problem, put simply, is that they're no longer a defensively-stifling team.

But here's the question: where they ever? Maybe not. From Senators Extra:

If there is one recurring trend with the Senators under Paul MacLean’s tenure as coach, it is that they play high event hockey; that is, the Senators produce and allow a disproportionate number of shots relative to their NHL peers.

[...] In each of MacLean’s full seasons as coach, Ottawa has finished among the top 10 teams in the average number of shots per game and the bottom 10 teams in the average number of shots allowed per game.

It’s not like the 2012-13 Senators were a defensive juggernaut that lapsed into mediocrity this season. If that were the case, the team would not be allowing shots at a pace not seen since the formative days of this franchise’s modern existence.

The Senators simply were not a great defensive team to begin with.

So how do we explain last year's numbers? Simply, exceptional goaltending.

Craig Anderson provided it, and when he went down with an injury, Robin Lehner and Ben Bishop played just well enough in his absence for the Senators to continue getting by. Ottawa finished the year with an even strength save percentage of .936, and the best shorthanded save percentage in the league at .922.

These aren't sustainable numbers, especially for a team that plays run-and-gun hockey. Over a full season, they're bound to normalize, as they have this year. But the Senators didn't have to play a full season in 2012-13, because the lockout wiped out everything before the hyphen. In so doing, it also happened to chop off the section of the season where things might have come back to earth.

Or, at the very least, push it to the year.

(This graph, via Travis Yost, demonstrates the way the percentages have turned on Ottawa this year after being so favourable for much of Paul MacLean's tenure. You can also see where things started to go south towards the end of last season, but fortunately, the schedule ended before people really noticed.)

And so, instead, the Senators, their fans, and plenty of pundits went into this year thinking this team was close.

They weren't. Last year's team was just lucky.