However Herbert already has a lot on his plate - now he has a rookie offsider. Last year, Herbert could lean on Luciano Trani, who would run most of the training sessions and provide valuable tactical input on match days.
Trani had a huge database of information about opposing teams so each Phoenix player went into a game knowing as much as possible about their opponents.
It is a lot of slack for Greenacre to pick up, especially when he is also concentrating on staying fit and sharp.
It's expected Greenacre will run the front third, leaving Herbert to look after midfield and defence, analyse the opposition, study opponents, run training sessions, prepare tactics and game plans and assess possible transfer targets during the season.
And if Greenacre is on the field, Herbert will have no one to bounce ideas off during games.
Herbert loves his job and pours hours into it but the Wellington bench still looks thin. The Phoenix have Herbert, physiotherapist Wayne Roberts, strength and conditioning coach Lee Taylor, a yet to be appointed goalkeeping coach and Greenacre in a part-time capacity.
In contrast, Sydney have nine technical staff, while the Brisbane Roar have 10, including two assistant coaches, a goalkeeping coach, a club doctor and three sport scientists.
Sure, the picture is blurred somewhat, as the Australian franchises have more teams, but it also paints an ominous picture - rarely has success in professional sport come after cutting corners off the pitch.