When Nathan Coulter-Nile walked in to bat, Australia were tottering at 147 for 6 in the 31st over. At that stage, according to ESPNcricinfo's Forecaster, Australia were expected to finish on 232, which would have been well below par. The Forecaster calculations are based on the batting quality of the remaining batsmen, the overs remaining for the bowlers, and the match context. Given that six wickets had already fallen cheaply and Coulter-Nile only had two 50-plus List-A scores with a highest of 62, it was fair to assume that he wouldn't cause too much damage.
What followed completely changed the complexion of the match, as Coulter-Nile chanced his arm early on, and finally ended up smashing an astonishing 92 off just 60, the second-highest ODI score ever by a batsman at No. 8. He had a control factor of just 65%, but that didn't matter given his strike rate of 153. When he finally got out in the 49th over, the projected score went up to 296, though Australia finally finished on 288.
The impact of Coulter-Nile's runs is apparent in the change in projected scores, which is also why his Smart Runs was a whopping 129. Smart Runs measures the actual worth of runs scored, taking into account the match situation and context, bowling strength, and contribution by other batsmen. During the period when Coulter-Nile was at the crease, the batsmen at the other end contributed only 36 from 46 balls - a strike rate of 78 - while he went at almost twice that rate.
West Indies did have one clear chance to dismiss him, but Shimron Hetmyer spilled the chance at deep midwicket. Coulter-Nile was then on 61 off 44, and went on to score 31 more runs off the 16 balls he faced after that (including the ball off which he was dropped). According to ESPNcricinfo's Luck Index, had he been dismissed then and had the remaining batsmen played those 16 balls, Australia would have finished with 23 fewer runs.
Given the margin of defeat - just 15 runs - Jason Holder was justified in his post-match comments where he mentioned that lapse: "We dropped Coulter-Nile when he was about 60-odd and he got about another 30 runs. That was one pivotal moment." West Indies were hard done by with other umpiring errors which they couldn't do much about - the marginal lbw decision against Chris Gayle cost them 21 runs - but the Hetmyer chance was one which was in their control.