Stop the Capitals' power play, stop the Capitals.

It's a familiar refrain, even as this year's incarnation of the club is poised to be on the good side of 50 percent in both shot- and goal-differentials at five-on-five for the first time since Bruce Boudreau's last season behind the Washington bench. To wit, "as goes the Caps' power play, so go the Caps" doesn't hold up quite as well this season as it has in the past.

So far in 2014-15, they're 23-13-7 (a .535 win percentage) when scoring at least once with the extra man and 14-10-3 (a similar .519) when going oh-fer; in 2013-14, they were 24-11-5 (.600) when potting at least one on the power play and 14-19-9 (.333) when they didn't (the split was .620/.356 for the entirety of The Oates Error Era).

Still, as the playoffs approach, it's critically important that the Caps' get the most out of their biggest strength - that second-ranked power-play. In recent years, they've won games with the man-advantage, and lost series when it hasn't clicked. (Yeah, sorry about that last link.) If they want to make any noise this time around, they're likely going to need their power play to come through, and that means having the right guys on the top unit... and with four of the five positions pretty well fixed, what we're really talking about is having the right guy at the top of the 1-3-1 set-up, bombing away (or at least presenting the threat of doing so) and feeding Alex Ovechkin's one-time howitzer.

Back at the end of December, we took a close look at what was a bump in the road for the Caps' extra-man unit, with a focus on shot rate (Corsi-For per 60 minutes (CF60) at five-on-four). It's by no means a perfect measure of how well a specific power-play is performing, but it can certainly inform as to when there might be a problem, and there was - shot rate had plummeted and, with it, efficiency. With that in mind, let's take a look at the Caps' five-game rolling CF60 at five-on-four (via war-on-ice.com; all stats in this post through Friday night's game):

After a big spike for the first three weeks of November or so, the shot rate dropped and has bounced around a bit before bottoming out towards the end of February and then rebounding in a big way lately. Why? Let's overlay the percentage of power-play ice time for the Caps' top-three power-play defensemen - Mike Green, John Carlson and Matt Niskanen:

Well, that's pretty cool. Keeping in mind that the samples here are small (for example, the Caps have only spent a bit under 24 minutes on the power-play over the last seven games), it looks as though the first big spike was driven by Green and then Niskanen picking up when Green missed some time with injury. Then the rate dropped off, Green shepherded it through some ups and downs and the most recent spike has coincided with Green losing ice time (and missing time) and Carlson taking the helm (as he did to start the season).

Then again, the recent spike also coincided with the Caps facing Pittsburgh, Carolina, Toronto, Columbus, Minnesota and Buffalo (two good shot suppression teams, three bad ones, and a middling squad) in small minutes - over those half-dozen games, the Caps have attempted 61 shots in their 23.4 minutes on the power play, which is great... but a tiny sample. (The downturn that followed includes the losses to the Rangers and Dallas, both of which featured the Caps generating shots at a lower rate.)

So here's the question - with the four forwards on the top power-play unit seemingly set in stone (and for good enough reason), and Carlson manning the point of late... should he be? Or should Barry Trotz hand that role back to Green? (We'll leave Niskanen out of the discussion for now, as he seems a highly unlikely option.) Let's look at a few things:

Overall Shot Generation

That was the focus above, so let's look at it here. Using Ovechkin and Nicklas Backstrom as a proxy for the top power-play unit (PP1), that unit with Mike Green has generated 114.07 shot attempts per sixty minutes at five-on-four and 59.76 shots on goal per sixty since the start of the 2012-13 season (that's the time frame for the stats in the rest of this analysis, and thanks to Muneeb for the data). To put that into a more intuitive rate, that's about 1.9 shot attempts and one shot on goal per minute on the power play (which is very roughly the length of the average PP1 shift). That may not seem like much, but it would be enough on its own to be at the top of the League in attempt- and on-goal rate.

John Carlson's PP1 blows that shot generation out of the water.

With Carlson up top, PP1 is attempting 153.89 shots and putting 87.01 shots on net per sixty, or 2.56 shot attempts and 1.45 on goal per power-play minute. That's a 35% increase in shots attempted and a 46% uptick in shots on goal.

When it comes to shot generation, it's not close. Advantage: Carlson

Setting Up Ovi's One-Timer

This is the bread and butter of the Caps' power play; everyone knows it's coming, but they still can't stop it. Our eyes tell us that Green is far better at feeding that puck right to Ovechkin's wheelhouse, while Carlson misses the target too often. Are our eyes right?

Green has eight primary assists on Ovechkin power-play goals this year and Carlson has four. Case closed?

Not so fast. Obviously those dozen goals are a small sample on which to base a conclusion, so let's expand a bit. With Green on the ice, Ovechkin is getting 19.47 shots on goal per sixty minutes on the power-play, and with Carlson out there, that number bumps up to 24.74 (a 27.1%) increase. Might those shots be lower-quality (fewer one-timers, etc.), due to worse passes? Sure. But Ovechkin's goals-per-minute are about 23% higher with Carlson on PP1 versus Green, so he's shooting and scoring more with Carlson out there, and since the start of 2012-13, Carlson actually has just two fewer primary assists on Ovechkin power-play tallies (16-14) in 87 fewer minutes (308.22 to 220.67). So maybe perfect placement of that pass isn't all it's cracked up to be... or maybe our lyin' eyes aren't to be trusted. Advantage: Carlson

Shot Threat From the Point

Without credible shot threats elsewhere on the ice, teams can cheat to Ovechkin and watch the Caps try (and fail) to force-feed him. We've all seen it. So who's shooting more from the top of the 1-3-1? Carlson, unsurprisingly - he's at 38.88 shot attempts and 17.95 shots on goal per sixty on PP1, whereas Green lags far behind at just 23.36 and 9.93, respectively. That puts Carlson at 66% more attempts per sixty and a whopping 81% more shots on goal (not to mention a 5-3 advantage in shots in goal). And in case you need a reminder of what it looks like, here's this from last night, which includes setting up a patented Ovechkin one timer, and then launching a shot (and goal) of his own: This one's not close. Advantage: Carlson

Conversion Rate

Ultimately, this is what matters (though it's certainly worth noting that shot-generation is a better predictor of future power-play success than shooting percentage). With Green out there on the top unit, they've converted at a rate of 11.29 goals per sixty minutes at five-on-four. That's a big number that's higher than any power-play in the League's scoring rate... but increase that rate by 20% and you get to Carlson's PP1 goals per sixty rate of 13.59. Advantage: Carlson

Other Factors

Each defender has been on the ice for a five-on-four shorthanded goal-against. Who cares. What we should care about is the role each plays while he's not on the power-play. Carlson is the team's top defenseman, logging nearly 18.5 minutes per night at even-strength (more than three minutes per outing more than Green) and three minutes per game on the penalty kill (2.5 minutes more than Green). You'd think that would give Green an edge here, in the interest of keeping Carlson fresher for those minutes (including those high-leverage penalty-kill minutes). And speaking of high-leverage situations, the Caps power play is exactly that, and this is where they can get the highest return on their investment in their two-time Norris Trophy finalist (who didn't earn that line on his resume for his defense). The Caps kept Green at the trade deadline - might as well get their money's worth out of him. Advantage: Green

Pulling it all together, the Caps' power-play is a juggernaut, and it has two options for point-man, both of whom are keeping the unit chugging along at elite levels. But the top unit shoots more and scores more with John Carlson than with Mike Green. Alex Ovechkin shoots more and scores more with John Carlson than with Mike Green. And John Carlson himself shoots more and scores more than Mike Green. There are reasons that, despite these advantages, Green might be the preferable option for that coveted (and no doubt money-making) role, but in terms of power-play effectiveness, it would seem that John Carlson is the better option.