This card looks pretty good to me. It seems like the kind of card that people would start talking about and you'd see it go up in pick orders over time. It's a good surprise blocker (kills the ubiquitous 2/2 fliers that cost 4), and its surprise evasive damage. But the 2 power for 5 mana makes it seem underwhelming on first looks. Comparing this with Skyhunter Prowler, you're paying and extra

for +1/+1 and Flash. Flash seems to be worth about .5 mana, and the other 1.5 seems fair for the P/T boost. I definitely wouldn't expect these guys to table, which means they aren't 23-24. At 5 mana, you don't want too many of them though. For this to really be overcosted, it should be 5W. At that point, it's still playable, but you definitely wouldn't want multiples.
Either way, it's clearly useless in constructed. Still, good card.