I was posting this in the Buffalo PGT, but it occured to me I'd like to have a bigger discussion so instead, I'm cutting and pasting it into a new thread.
Note: I have trouble focusing long enough to understand lengthy descriptions in glossaries, etc, so most of my interpretations are heavily coloured by my own assumptions regarding patterns and variances/differentials, etc. I did have to look into the specific criteria of an "Expected Goal" becuse I kept arguing with myself about the numerous ways in which not every goal opportunity is the same. This was a long process because I couldn't just read through a description and understand it completely, so I had to keep googling everytime something occured to me... "wait, what about shot selection... what about shooting ability... not every player treats a loose puck in crease the same way... also, what about angles... 6 players can use the same shot from the same spot on the ice, and put the puck in 6 different spots on the net..."
Anyway, this isn't about me. I'm just saying all of this to say it there's anything I'm wrong about, please correct me. I'm not trying to make people teach me how to read advanced stats, it's just that I'm positing quite a few conclusions here, so if I'm not interpreting a stat properly... you know, it's like please tell me if I have lettuce in my teeth.
Ok, here's what I was going to post:
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The Flames this season are actually one of the best teams in the entire league 5v5 (7th overall in xGF%). We've played well enough to put ourselves in postion to score 69 times (68.6 xGF, 10th best!), but the problem is that our GF Above Expected is dead last in the NHL at a whopping -17.6 (only 51 actual goals for). Meaning we're not just "not scoring," we've actually scored 18 less goals (rounded up) than what would be expected from us if all of our shooters had league-average shooting ability. Note that the high xGF% means that our systemic play is actually putting us in position to be a high-scoring 5v5 team. We're just... not actually doing it.
At 5v4, the Flames are second last in the NHL with an 82.92 xGoals%, which is both an indictment of our PP personnel as well as our PP itself. The 5v4 data shows that, while we are 5th worst at capitalizing on the PP (-4.6 GF Above Expected), we're middle of the pack at 19th overall in xGF (16.6). Because of our 5v5 Goals Above Expected being so low, it's probably safe to assume the fault-distribution on the PP slants more towards the players (shooting and/or system execution) as well, but there's also a potential argument to be made against the system itself.
On the defensive side, we've allowed only 60.3 5v5 situations that were expected to result in goals against, which is 12th best in the NHL. Our actual goals against is 61, which is almost a 0 differential (0.07 GA Above Expected) - so our goaltending isn't allowing more than it should, but it isn't preventing more than it should either. This is a step down from last year (sophomore slump?), but it's not like we're losing games because of goaltending.... we're just not winning them because of goaltending like we did last year. This is based on our entire body of work this season, keep in mind. Have there been specific games both won and lost by goaltending for us? Yes, but it's evened out over the course. Just outside the top 10 in 5v5 Expected Goals Against is really good though.
On the PK (4v5 only), we're getting almost top-10 goaltending, with a -3.52 (11th) GA Above Expected... however, we're sitting at 23rd overall in both PP Goals Against (17) and Expected PP Goals Against (20.52). Again, is it PK personnel (commitment, read/react, panic threshold) or the PK system? I mean the PK is generally more about execution than system anyway. The chances of using the wrong system to counter an opposition team's PP are probably not that high. It does get infinitely more tricky though against high-IQ teams like Forida (when they're healthy) though, as they have players that can change PP systems on the fly while in the O zone. (Which is why Barkov is such a valuable player. He can switch things up on the PP, and also read and react well on the PK. A cerebral masterpiece of a player!).
Addendum
Continuing with the PK (4v5 only), this is a touch on the silly side (but everything is interesting to me, so it might be to others as well), but we have the third-best GF Above Expected in the league (1.3) (1st is NYI with 1.7). We are tied with six other teams for the second most shorties (3), but are only 23rd overall in expected shorties, meaning we're actually over-capitalizing on our chances when shorthanded. It's a pretty stark contrast to our 5v5 and 5v4 finishing ability, and I'm not yet sure why that is. Shorties tend to slant more towards breakaways and odd-mans vs zone presence and puck possession, so it's possible our PK personnel also slant that way in terms of shooting ability. In the grand scheme of things, though, I'm not sure how much onus teams place on the offensive production of their shorthanded units (outside of perhaps EDM, where they seem to thrive more in any situation that has less total people on the ice). This was just something I looked into as a bit of brain-dessert, so to speak.
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And this is where I started getting bored lol. There's way more I could attempt to get into, but I need to do literally anything else now.
Edit: For the love of god, this thing is like 60% about me with only 3 paragraphs that have anything to do with the actual topic. I didn't intend things that way lol. Please feel free to ignore anything outside the dashed lines if you want (I guess except this part, otherwise you wouldn't see it.)
Edit: Wait. I had the first dashed line in the wrong spot. Maybe the "me to topic" distribution isn't as bad as I first thought lol.

Edit: I rewrote some stuff. I have to do a lot of cutting and pasting becuase my sentences often start on one topic and then end on a completely diferent one. And when I've mentally moved on, I tend to miss things that need to be rewritten becasue they no longer match the tone of their surroundings.
Edit: Another pass for typos etc (I had the xGF at 61 instead of 69, for example). Also cleaned up some wording.