"Today's loss isn't ideal for the confidence,'' he said. "We're not high in confidence at all and they are, so that's probably hurting us because they seem like a confident team.
"We've got to find some confidence somewhere, whether it be in the nets or, hopefully, out in the middle.
"We need to find it in the next game or two, otherwise the series will be gone before we even know it.''
With the Black Caps having struggles with bat and ball throughout the three games, it's hard to know from where that confidence boost will arrive.
After being bowled out in both T20 matches, today was the first time the tourists had completed their allotment of overs. The bowlers have managed to take only eight West Indian wickets across the three games.
"We needed more runs on the board - it didn't really help the bowlers trying to defend a target of 190,'' Watling said.
"We also need to figure out how to take some wickets over here. The wickets are reasonably flat for the quicks - there's not a lot of swing or seam - so we need to find some ways of restricting and building up some pressure.''
The news from the treatment room certainly won't brighten the team's mood, with allrounder Andrew Ellis facing time on the sidelines after injuring his left quad muscle while running between the wickets.
An early assessment suggested a grade one strain, with the allrounder unable to take the field during the second innings, but more will be known within the next 24 hours.
With Ellis' injury and his fellow batsmen falling around him, Watling was the only bright spot in the Black Caps' turn with the bat but the 26-year-old was left a little dissatisfied with his efforts.
"My gameplan was to try and stay there for a little while and try to set a little bit of a platform so we could at least bat through to 45-50 overs. I was a bit disappointed not to get 20 more runs and boost the strike rate up around 80.''
He at least managed to see his side through the the 48th over before falling, but the New Zealand total was never going to be enough.
"We fell a good 50-60 runs short on that wicket and we didn't quite deliver with the ball,'' Watling said.
Kyle Mills, who took the wicket of Lendl Simmons and ceded just seven runs from his five overs, was the only bowler to find some success as Chris Gayle again ran amok.
Jacob Oram returned from the knee injury he sustained in the opening Twenty20 last week, but he went wicketless from his five overs for the cost of 37 runs.
The second one-dayer is on Sunday morning.
