mindmasher
Registered User
Even with all that said, I still think GVT has serious limitations. I'm just arguing that the goaltender position, typically speaking, is the most important single player on your team.
GVT tells us that 6 out of the top 10 NHL players are goaltenders. Do you believe this to be true?
0 out of 10 are defenders. Do you believe this to be true?
Well Taco, it's funny you bring this up. I think there are a lot of smart people - Dejardins and Dellow for instance - who have argued repeatedly that unless you are getting an elite level goalie, save your money because performance variations amongst middle tier goalies is negligible.
In other words, goaltenders are very important, but tend to be very close in ability. Therefore unless you have a bead on a Tim Thomas type, you should be spending small dollars on a couple of capable NHL starters who simply don't have many teams to play for.
In another way, goaltenders can also be a considerable source of lost points on a team if you deign to start a guy who is performing considerably below replacement level.
So yes, ultimately, goaltenders have little value in that there are a lot of good cheap options. You see some GM's following this principle closely. Detroit, Chicago, Avs, Philly, Phx, etc.
I'll play devil's advocate (since I'm widely known as the biggest "goalie homer" on the board).
Suppose that goaltenders have much more influence on the game than either forwards and defensemen (and let's suppose that it isn't even close). That's different than what's being considered here, which is "how much more value does Goaltender X bring to a team than a replacement-level player?".
If we pictured a world where goaltenders had the most influence on the game, but where all goaltenders were identical, then Goaltender X would have no value (because you could go down to the goalie store and get another one just like him).
To summarize: the question here isn't whether or not a goaltender has value. The question is whether or not he has more valuable than a team's next option.
The problem is with the definition of replacement level - Ryder's Player Contribution (I'd hazard a guess that GVT has a similar definition) defines replacement level as the level that a minor-league player would perform at if called up.
So what these stats are actually measuring is "how many wins did the Bruins gain with Tim Thomas in net, compared to if they had Anton Khudobin in net" rather than comparing Thomas to Rask (which is what you are suggesting).
This is why the likes of Antti Niemi appear higher than, say, Ryan Suter on a GVT list. Niemi may not be an elite goalie, but simply by not making rookie mistakes, he's already contributing a lot of "value over replacement level" to his team.
So what these stats are actually measuring is "how many wins did the Bruins gain with Tim Thomas in net, compared to if they had Anton Khudobin in net" rather than comparing Thomas to Rask (which is what you are suggesting).
That was a great post and I think we are on to something with the 15% skaters attribute toward SV%. The threshold seems accurate and correct.
While I don't have the data to back up this statement (yet), I'll use TBL and TOR as my prime examples over the last couple of years. Still, 15% of a SV% is not much to spread across a team of skaters. 1 player take 85% of the blame, while 15-18 skaters SHARE 15% of it. No QualComp adjustments to the top defenders. Just a blanket, equal share of the results. Goalies should NOT be evaluated against their total SV%, but things (GVT) should be split intelligently accounting for 5v4 SV%, 5v5 SV%, etc.
Teams have much more affect on 5v4 SV% (probably higher than 15%).
Typically GVT has been brutal on the goalies for both of these generally poor defensive teams (no matter who was put in net). GVT places 85% of the blame on the goalie's shoulders for this resulting in "the worst" goal tenders getting -20ish GVTs which is far and away much, much lower than any other skater. If GVT truly was accurately reflecting these goalie's performances, we'd see these teams quickly replace them and "solve" their defensive problems. We all know that isn't the case for the poor TOR fans.
The defenders for these very poor teams do not typically shoulder the blame and post + GVTs despite getting dominated and feeding their goal tenders to the wolves. If we were dealing with just a "poor" goaltender, I'd expect to see backups and other options played for these teams with some success, but that doesn't seem to be the case. I don't think that SV% for a goalie is as isolated in every case as we'd like to assume. There needs to be a team adjustment for their PK ability and rate at which they take penalties (cough, TOR).
There are teams at the extremes that have a huge impact on their goal tenders performance and SV%. BOS at the top and TOR at the bottom. Looking at these teams PK%s is a good place to start. Looking at total SV% alone also has to stop IMO in the GVT calculations to progress it to the next level.
Once this happens, GVT will probably start to gain more popularity.
I agree that PP and PK effectiveness should be factored out and attributed first if possible.
As I said in my post, and you seem to agree, it's very possible that goalies are being given too much credit for the difference between their SV% and threshold. However, just to be clear, GVT's author says that goalies on the same team have only a 15% correlation in SV%, but he does not fully attribute the value from the difference between goalie's SV% and threshold (4% more goals than league avg.) to the goalie, not even 85%. He attributes only 75% of this value to the goalie and terms it "Goalie Responsibility."
The question is whether that 75% is the right number and whether the other thresholds (such as 75% of team's avg. per-minute scoring production) are fair and whether other parts of the system are accurate/fair.
I think we are starting to come to the conclusion that the adjustment may not be the same % allocation for team/goalie for every team. While 15% (or 25%) may work as an NHL average, there are certain teams at the extremes where that % may need to be adjusted based on PK minutes and success during those minutes. I think we may be able to borrow from some of the great work on expected goals for goalies that use these inputs.
Teams should shoulder more of the scaled SV% credit with 5v4 min/5v5 minutes as the deciding factor or input.
This still comes back to the tough GVT pill to swallow of a single player costing his team 20+ goals over a replacement goalie. I can't see that ever being the case (unless I personally was playing goalie for said team). NHL goalies just aren't "bad" to that order of magnitude outside of MAF in the 2012 playoffs.
I think offensive GVT is just about perfect, and we may be able to refine dGVT and gGVT to match it.
Does anyone have a GVT calculating spreadsheet to start from?