Sometimes you have to gamble a bit on younger players.
With Cromen, we've pretty much seen the best he can offer. He's another Lekr0 type player - good enough for a tier 2 team and will produce a nice highlight clip occasionally... but we're probably not going to see him in the HLTV top 10 ever.
With Brollan, the potential is definitely there. If he keeps improving up until his early 20s as most players do, then it's very plausible that he could break into the HLTV top 10.