The premier men's club upset powerhouses Complete Flooring Napier Technical Old Boys just before Christmas in the Bay final before advancing further than last summer's qualifiers, Heretaunga Building Society Cornwall CC, who lost away to Greytown CC at the same stage.
Sinclair said for most NOBM players it was a test of where they want to be in their careers.
Greytown, without injured paceman Seth Rance, made a bolshy start on 108-1 but the rot set in as they slumped for 216.
Brendan Quinn got 3-50 but Sinclair (2-30) and Anoop Renuka-Prajad (1-32) were the most frugal.
In reply, the hosts overhauled the target with 218-5 in 41.1 overs.
Opener Damien Scott scored 66 runs, Sinclair made 64 at No 4 while the other opener, Jaspeet Singh, added 45 to the cause.
The NOBM players had tied in a match against Ruahine Motors Ford Central Hawke's Bay in their Property Brokers Hawke's Bay 50-over premier men's club competition the previous day at Nelson Park.