Of course, size is not everything, but its very big. When you take a total of one player with size with a late second rounder, its tough.
Undersized guys can be successful, but not usually alone as they tend to need size alongside them. On occasion, the real greats can drive the play themselves at that size, but most are paired with 6'3, 210+ linemates.
This is why I think that Ek, smith, and celly can be successful if they can get beef like cherny, haltunnen, or musty alongside 'em. but, you can see how wennberg has been the only top 9 forward who can actually possess the puck for more than a few seconds, and without more guys of that size or bigger, the sharks just cannot control games.
The point still is that your analysis is flawed because none of those players except maybe Gushchin have failed to live up to expectations purely or largely because of size. Small guys can succeed, but small guys that lack NHL caliber skills won't, just the same as big guys without NHL caliber skills. Merkley, for instance busted because he has a 10-cent brain and doesn't defend.
The Sharks' struggles at the draft table in that period are because they took guys with big flaws that couldn't be overcome, not that they drafted guys who were too small.
Besides:
2006: Ty Wishart (6'4, 222) - 21 NHL GP
2007: Nick Petrecki (6'3, 227) - 1 NHL GP
2008: Justin Daniels (6'2, 195) - never made it above the low minors
2009: Taylor Doherty (6'7, 235) - topped out in the AHL
2010: Max Gaede (6'3, 200) - topped out in the ECHL in his only pro year
2011: Justin Sefton (6'3, 226) - Played 2 games in the ECHL then was in USports (Canadian University league) for 3 years likely as a guy who was there to get his degree but also play hockey
2013: Mirco Mueller (6'2, 176) - Was basically force-fed 185 NHL games and we watched him drown
You can make exactly the same list of "look at all this failure!" picks for guys with size. They failed not because they were or weren't big, but because they sucked. The successes in that range of years were McGinn, Couture, Coyle, Hertl, Nieto, and Tierney and none of them were particularly big besides Hertl and Coyle.
All things being equal, is having size better than not having it? Sure. But like drafting for position, you don't draft for size unless it breaks a tie or pass on a guy because of size unless he's so small that you worry his skill level won't overcome it.
Like, for instance, I have talked up Cameron Schmidt all year because he's the top draft eligible from my favorite WHL team and he's an incredibly dynamic offensive player when he's on his game, having scored 40 goals in just 61 games and was better than a point-per-game. But I don't fault any team that doesn't want to take him because he's inconsistent and streaky enough that you don't get his A-game every single shift and he's like 5'7 on skates. That's an instance of size mattering. But I'm not passing up skilled 5'11 guys in favor of 6'2+ guys as a broad drafting strategy just because some of those 5'11 guys are going to bust.
