It isn't 100% but my sense is that most kids post-draft don't grow any taller (they do put on weight). No doubt you can find spot examples that do but I'd need to see a more thorough assessment to believe it accounts for more than that. Besides, the top 20 scorers in the CHL generally aren't 17 year olds and are probably more 19 and 20 than 18 year olds.
Well I did acknowledge that Ehlers and Virtanen were not good cases to be impacted by this analysis, given both of them being close to the 6 foot cut-off. It was meant to be a more general assessment of the bias towards size in the NHL vs junior. I don't actually see much risk in Ehlers' height nor do I see much advantage in Virtanen's height, given that they are about 1 inch apart. Their weight and frame is a different matter.
So if Ehlers' height isn't an issue then why bring up the stats regarding the number of players below 6'0?
And regarding weight I showed in the Virtanen thread all the weights of top-10 forwards in their draft years from 2005-2008. Ehlers is currently at 176, here's all the players at a similar weight or less:
Backstrom: 183
Hodgson: 182
Crosby: 180
Stamkos: 178
Brassard: 175
Turris: 165
P. Kane: 162
Filatov: 159
The only true bust from that list was Filatov, who as well as being 159 i his draft year got fed up with his situation in the NHL and left to the KHL, he might very well be a decent NHLer if he had stayed. So I don't see why his weight is an issue based on historical precedent.
I don't know that I agree with just removing the 5'9 players since their prevalence in junior speaks to the fact that size is much less important in the CHL but much more important in the NHL. Stating that 5'9 is a 'floor' or 'minimum' doesn't mean that size stops being a factor beyond that level. It merely stops being an absolute (or near absolute barrier). I believe it still favours larger size beyond 5'9 however other factors start to come into play (absolute skill level, strength, etc). Below 5'9 very few players can make it even with elite skill levels (the odd exception of course exists).
Size is less important in the CHL than it is in the NHL, but only for players below that threshold(whether 5'9 or 5'10, the point is moot w/ regards to Ehlers).
Again I clearly stated that weight continues from CHL to NHL hence why I opted not to use it in my analysis. And in general most kids will have their NHL height in junior but not their NHL weight. This is my concern with Ehlers, and was even when I was pushing for him in Feb-March of this year (before I turned more in favour of Virtanen). The fact that he started at such a low weight (163) and has put on a lot of weight in a short period of time (+13 lbs) but is still well below NHL average (195-205) does make me question whether he can ever get to a level where he won't be easily outmuscled at the NHL level. Some players can be short and incredibly strong (Crosby) while others simply never gain enough strength to be as effective as their skills (Raymond). It certainly isn't a given that Ehlers won't get there, but it also isn't a given that he will. It's a legit question, just as you question Virtanen's production.
Putting on 13 pounds between ages 17-18 is hardly shocking especially for a professional athlete. I already showed above the players at a similar weight in their draft year and it doesn't seem like any red flags are present there.
If you ignore TOI completely, then yes Ehlers had a higher GPG. If you factor in TOI, which I did based on the extraskater.com estimates last year, then Virtanen actually had the higher GPG.
Goal scoring per TOI is not a valid stat to use when comparing players imho(even before factoring in that those are very rough estimates). Otherwise you could end up concluding that Bergeron was a better goal scorer than Ovechkin last year, which is clearly not the case. Especially when you are balancing out the lesser PPTOI/G without accounting for the fact that you're playing against weaker competition on the 2nd PP unit.
Not to mention the factor I mentioned before that fatigue plays a role as well, there's a reason why the Sedins/Kesler crashed and burned last year after being played 25 minutes per night, they would almost certainly have gotten more points over the entire season if played closer to 20 minutes.
Of course this is where we differ. You prioritize Ehlers puck skills and vision more than Virtanen's physical element, just like you prioritized Nichushkin's size and speed more than Horvat's defensive skills. All have an impact on the outcome of a game and it is hard to say if an extra 5 goals and 10 assists a year contribute more than being better at retrieving the puck on a forecheck or being able to battle around the net more effectively. At the end of the day, it will come down to the magnitude of the gaps between these players. You can't simply say Ehlers is better at x, y, and z while Virtanen is only better at x so take Ehlers. HOW much better each player is matters. How many more goals (if any) will Ehlers score is what counts, not merely that he may score more goals. And HOW much more effective Virtanen is at puck retrieval (if at all) matters more than simply being more effective. We don't know the magnitude yet because both of them have not applied their games at the NHL level.
This is not surprising given that we place different measures of value on different things. Fortunately we didn't draft Virtanen to be the 17 year old version of himself in the NHL so how they are now matters less than how they are trending. While it will probably be construed as 'spin', I would personally wait until Jake is performing at his 'best' level before making this comparison. The surgery and missing TC (both NHL and junior) along with the first dozen games of the season have him behind the 8-ball. But his play has been steadily improving (0.90 PPG, selected a star 3x in his first 11 games, 1.44 PPG, selected a star 5x in his last 9) and I believe it will continue to get better after the WJC. If he can be even close to Ehlers in PPG - say Virtanen at 1.5 and Ehlers at 2.0 - while getting lower TOI and playing a more physical style game then I will be satisfied (though I realize you may not).
Using this logic you could justify virtually any pick, based on the fact that "we don't know anything about them at the NHL level yet". Does Ehlers producing >50% more in junior translate to 15 more points at the NHL level? Would you take a 75 point Patrick Kane over a 60 point Milan Lucic? These are all speculative, and I prefer to compare their actual current attributes then to try and assume what each player will be at the NHL level.
Based on what I've seen, the only aspect in which Virtanen is superior than Ehlers is physicality. I do not think it is good practice to take a player whose sole advantage is physicality(again, based on my own opinion), and I haven't seen anything that supports Virtanen being inherently better or safer due to the difference in size.