"We picked the fielder out on the weekend. A few bad umpiring decisions, and I guess some poor shot selections," said Rayner.
"When [Manawatu] batted, they put them in the gaps. They are the best team by a long way."
Manawatu, with 40 points, are now well on top of the Hawke Cup standings, having won every game outright this season including an extremely rare innings victory over Hawkes Bay in November.
Hawkes Bay will play the dejected Wanganui at Victoria Park on January 25, hoping Manawatu have an absolute shocker against Taranaki so they have an outside chance of tieing the front-runners on points and getting over the line on run rate.
For Wanganui the next verse is the same as the first trying to find some batting form.
The side will hopefully have Henry Collier and Brett Cameron back from Central Districts duties to face Hawkes Bay, but coach Rayner said even with nothing to lose, they cannot afford to experiment by bringing up anyone else new from the club scene.
Nor could any more be done for team preparations, which involves Wednesday practice, as the players needed to do their own work to strengthen mentally.
"Our biggest problem in Wanganui is player depth there's not a lot of guys up to playing Hawke Cup cricket at the moment and those that are, are already there," said Rayner.
"Maybe we can change our approach, more from the spinners and bring them on earlier.
"The boys, they all know their own game and should be doing their own thing. In the season, we can't really change too much.
"It's one of those seasons we're happy to see the end of."