The Caribbean team, who came into the series ranked sixth, two places above the Black Caps, lost the third Test on Sunday by eight wickets following a resounding defeat by an innings and 73 runs in the second Test.
"We definitely cannot continue like this," an exasperated Sammy said after the loss in Hamilton -- which meant New Zealand won a three-Test series for the first time in nearly eight years.
"A lot of tough decisions have to be made. Probably some careers are on the line. Could be mine as well," said Sammy.
"We've had sessions like this in the past three years. We do well in one session and don't back it up in the other.
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"It's up to us, each individual as a batsman, to go out and if we have to get ugly runs, get it. Just do whatever is necessary to put the team in a good position, and we've not been able to do that.
The West Indies had no answer to New Zealand's pace attack led by Trent Boult, who took 20 wickets at 15.40 in the series and Tim Southee, who claimed 18 scalps at 18.11.
Darren Bravo's first Test 218 and centuries from Shivnarine Chanderpaul and Denesh Ramdin in the West Indies' first innings of the third Test were rare bright spots but around them wickets tumbled, as Sammy lamented an inability to forge partnerships.
"It's up to us as a batting unit, the two batsmen out there, to form a partnership and we were just not able to do that," he said.