There have been plenty of polarizing opinions in the last few days as NHL teams have started making their moves, and the Buffalo Sabres fans have had their own thoughts around the additions and subtractions made so far.

Let’s recap quickly, the Sabres traded away Ryan O’Reilly to St Louis Blues, getting Vladimir Sobotka, Patrik Berglund, prospect Tage Thompson and two picks. Separately, Buffalo added Carter Hutton, Scott Wedgewood and Scott Wilson.

There are various ways of looking at the net effect of the changes the Sabres have made this offseason, but for discussion sake let’s use ‘Goals Above Replacement’ (GAR) value today.

Click here for an in-depth explainer on what GAR is, it’s positives and downsides and more - bit for our piece here, this is basically what it is -

In concept, GAR is a one size fits all number that encapsulates how valuable an individual player is in terms of on-ice play, relative to a ‘replacement level’ player. A replacement level player is a player of a caliber such that they are readily available and can be acquired and played at a moment’s notice. Think along the lines of the players who shuttle waivers every year, or are your emergency callups from the AHL. A replacement level player is one of those. An example would be a player like Byron Froese Seth Griffith - a good player in the AHL who becomes very limited at the NHL level.

How is it calculated?

The short version is that player value is decomposed into six categories: even strength offense, even strength defence, power play offense, penalty drawing, penalty taking, and faceoffs. Value is calculated in each of these categories, usually by a regression-based technique, and summed up for each player.

Click here for a detailed explanation.

Sean Tierney, who does excellent work on the Tableau platform charting various hockey metrics, put together two tables to measure the impact of free agency so far on all the NHL teams, the first being the additions and the second showing the net value.

Off-season additions



Here's a look at which teams have added the most this off-season through signings and trades.



*Fun note: all of NYI's additions have carried negative values (i.e. below replacement level)* pic.twitter.com/cD2hKfVi6o — Sean Tierney (@ChartingHockey) July 6, 2018

Off-season +/-



A look at the value added and lost by teams so far in this off-season (including signings and trades)



Buf, Car, Phi, and Cgy have made the most net gains.

Ott, Bos, Wpg, and Nyi have suffered the greatest net losses. pic.twitter.com/058NqcBXZQ — Sean Tierney (@ChartingHockey) July 6, 2018

There is a disclaimer when using GAR though -

Where GAR stands out from the pack is that it makes a real attempt to adjust for these contextual factors impacting a player. How often do you see someone dismiss a player for playing against easy competition, or getting favourable usage. By using GAR, we can adjust for those factors in a quantitative way. At the very least, GAR is a valuable starting point to get an idea of what a player’s worth is, that can be refined and studied further. At its best, it is far more than that - its a concrete expression of how much a player is helping or hurting a team, and its certainly more robust than a pithy look at a player’s HERO chart with a quick Twitter quip. It’s not perfect, but it’s a strong improvement over many of the stats we currently have.

Per the GAR model, it looks like the Sabres General Manager Jason Botterill did well with the moves he engineered. Discuss below.