Age does matter, there's some studies that suggest late birthdays outperform early birthdays.
Jett for example was end of August 2006, only two months holder than Hagens.
It matters in terms of both experience, a very late birthday can be a year behind his draft group b/c he gets a top six role a year later in junior or is in the USHL instead of college, and physical maturity. At 17-18, nine months is a much bigger gap than say a year at 23-24.
Now in the case of Martone, you have a player who both physically matured early (man among boys) and is much older than most of his draft class, that would be a red flag to me.
Hagens is old for his class, but spent 18 playing college hockey against players who are mostly 20-23 years old. So it's not like he tore up the CHL as an older player.
On the other hand, O'Brien was 17 his draft season and played mostly against 18-20 year olds.
