It's all about the size difference. If NHL forward has 190lbs and NHL D-man has 220lbs, D-man will win 70% of puck battles and 90% of body-on-body battles. If heavier D-man uses his stick to create moment of inertia on lighter forward, forward has no chance. What he can do is just to learn how to fall down to reduce a chance of injury. In Connelly's case it was unfortunate he hit the pipe with his leg. But if you have 20 lbs less than opponent and you're going deep into a triangle with a goalie and D-man, you're asking for a trouble. It might be attractive, but it often cost you a lot.

Connelly's current draft profile (6'1" 160 lbs) is really not as much of a ding as you many think. Especially when you consider that he is one of the best skaters in his draft class. He is not someone where injury risk will be an unusually high factor. If anything, making defenders miss is one of his better attributes.

He was hurt two nights ago on a fluky play where he was spun around into the goal post (turns out there was no major injury). But it did exemplify his willingness and ability to skate into high traffic areas. As did his goal moments prior.

Also, he probably enters NHL around 6'1" 180 lbs. Size would not be a problem.

Here are some notable names and their CSS listed height/weights from there draft years. How many of them did you disqualify before their draft?

Johnny Gaudreau (2011): 5'6" -- 137 lbs
Reilly Smith (2009): 6'0" -- 157 lbs
Brayden Point (2014): 5'10" -- 160 lbs
Mitch Marner (2015): 5'11" -- 160 lbs
Joel Farabee (2018): 6'0" -- 162 lbs

Nikolaj Ehlers (2014): 5'11" -- 162 lbs
Nikita Kucherov (2011): 5'10" -- 163 lbs
Cole Caufield (2019): 5'7" -- 163 lbs
Artturi Lehkonen (2013): 5'10" -- 163 lbs
Elias Pettersson (2017): 6'1" -- 164 lbs

Clayton Keller (2016): 5'10" -- 164 lbs
Ryan Nugent-Hopkins (2011): 6'0" -- 164 lbs
Ridly Greig (2020): 5'11" -- 164 lbs
Alex DeBrincat (2016): 5'7" -- 165 lbs
Teuvo Teravainen (2012): 5'11" -- 165 lbs

Bobby Brink (2019): 5'8" -- 165 lbs
Oliver Bjorkstrand (2013): 5'11" -- 166 lbs
Vladislav Namestnikov (2011): 5'11" -- 166 lbs
Nick Cousins (2011): 5'10" -- 166 lbs
David Pastrnak (2014): 6’0″ -- 167 lbs

Kent Johnson (2021): 6'1" -- 167 lbs
William Nylander (2014): 5'11" -- 169 lbs
Jordan Kyrou (2016): 6'0" -- 169 lbs
Carter Verhaeghe (2013): 6'0" -- 170 lbs
Robby Fabbri (2014): 5’10″ -- 170 lbs

Lukas Reichel (2020): 6'0" -- 170 lbs
Logan Stankoven (2021): 5'8" -- 170 lbs
Sebastian Aho (2015): 5'11" -- 172 lbs
Nick Schmaltz (2014): 5'11" -- 172 lbs
Kyle Connor (2015): 6'1" -- 172 lbs

Morgan Frost (2017): 5'10" -- 173 lbs
Trevor Zegras (2019): 6'0" -- 173 lbs
Mathew Barzal (2015): 5'11" -- 175 lbs
Matthew Beniers (2021): 6'1" -- 175 lbs
Pavel Buchnevich (2013): 6'1" -- 177 lbs

Cole Perfetti (2020): 5'10" -- 177 lbs
JT Compher (2013): 5'11" -- 177 lbs
Connor Zary (2020): 6'0" -- 177 lbs
Wyatt Johnston (2021): 6'1" -- 178 lbs
Nico Hischier (2017): 6'1" -- 178 lbs

Warren Foegele (2014): 6'0" -- 178 lbs
Yegor Chinakhov (2020): 6'0" -- 178 lbs
Seth Jarvis (2020): 5'9" -- 179 lbs
Jared McCann (2014): 6'0" -- 179 lbs
Thomas Novak (2015): 6'0" -- 179 lbs

If the dman can catch the forward...what happens when he cannot?

Skating is a much more important factor these days. If one is small and cannot move well, they're toast. If one is small and moves very well, they'll be fine.

This size-trumps-skill trope died a couple of decades ago.