Besides what others have already said about experience and one-year under the OC's system, it wasn't a coincidence that he was named starter on the same day that the starting RB Porter was announced as out for the season. HJ was a track star in HS in Indiana and is pretty fast. If there's any knock on Helinski, it's his relative lack of mobility.
PS: from what I saw at practice, HJ doesn't really give up much, if anything at all, in arm strength to Hilinski. Others who attend more practices than me have told me they've seen the same. I'm excited to see HJ under a workable offensive system. I was very excited to see that he took all of the snaps against a live defense - no sharing as in past years.
PPS: A thing heard at practice about Bajakian's system versus McCall's: Mick's was hard to learn and easy to defend against. Jake's is easy to learn but hard to defend against. Love that.