Add fellow contracted players B-J Watling from nearby Te Poi, Ish Sodhi and Mitchell Santner and that makes a cracking ND contingent, if the major association was ever at full first-class strength.
You would have to go back to Canterbury in the 1990s to find a province dominating the upper echelons of the playing ranks to the same degree.
If you were an ambitious young cricketer keen to crack the national scene, what better way than moving to rub shoulders with Williamson et al on a regular basis.
The arrival of Wagner and de Grandhomme hints at the Mount's pull factor and the development of the Bay Oval precinct as a cricketing hub.
The locals' build-it-and-the-people-will-come Field of Dreams philosophy should be applauded.
Will New Zealand Cricket back Bay Oval in the next step beyond limited overs and age-group matches to host tests and a possible high performance centre?
If recent intelligence is correct, Seddon Park looks to have got the nod for the March day-nighter against Bangladesh but there's no doubt the players love the set-up across the other side of the Kaimai Range.
Hence the mass migration.
New Zealand prepared for their maiden home day-night test under the Bay Oval lights because of the superior lux quality. They also rate the pitch block – one of which was awarded ODI pitch of the year by NZC - for pace.
The oval amenities have earned plaudits, and there has been general discussion at NZC level around its capability as a high performance centre which might form what one source dubbed the "Lincoln of the north".
Perhaps that epithet would not be aspirational enough for local stakeholders. Will Lincoln - the South Island HP base - become the "Mount of the South"?
The centre is being considered as a base by India A coach Rahul Dravid later this year.
Dravid used the precinct when mentoring the Indian under-19 side to World Cup victory. That is some advertisement for the facilities meeting international specifications.
Despite the Mount's giddy ascension as a cricketing hub, perspective might be required when possible political machinations are factored in.
They are placing significant trust in NZC seeing them as a legitimate player rather than a pawn to play off against 1) Hamilton's Seddon Park, who are guaranteeing an upgrade to their lights so they can host the next day-night test and 2) Any longer-term development of a high performance centre as part of a revamped Western Springs cricketing precinct in Regional Facilities Auckland's Venue Development Strategy.
Bay Oval has become The Little Engine That Could on the New Zealand cricket scene because of a willingness to set high standards and ambitions about how they want the sport to grow in the region.
Now, with the help of NZC and a host of local playing talent, they need to know that they can.
