I think the winrate stats for Ambessa Top are being somewhat misinterpreted on the discussion of eclipse vs profane.
ESPECIALLY if we only take high mmr/pro stats (who KNOW what they're building AND who are against opponents who know how to pilot the counters) into account, buying eclipse itself is an indicator that they're in a bad counter-matchup/state in the first place which makes winning the game much less likely.
It's not that mostly "new" players are picking an "mathematically incorrect/inefficient" build path but that the game is more difficult to win relative to the Ambessa's performance in her lane matchup. Regardless of which itemization set outputs dps better in a vacuum, an eclipse first buy suggests the matchup is generally losing when played by two players in a similar skill bracket, which denies gold and pressure and lead compared to lethality in an already winning matchup. Already being in a disadvantaged lane from loading screen is what lowers the winrate, not the mathematical efficiency of each build.
Trying to interpret the stats past this initial understanding requires more parameters, but even when you look up matchup stats like Ambessa vs Renekton in the last 30 days on lolalytics, you have around 200 games of profane(53.6% wr) vs 5000 games of eclipse(48.8%) in D4+. Not only is the variance in sample size too small, making the margin of error overlap with the difference with the winrate, the p-value for a 2-tailed distribution is ~16%(much larger than the accepted <5%), meaning there's near ~16% chance of the difference in performance being due to random chance. This is assuming the win/loss is solely dependent on Ambessa's performance, and not accounting for the infinite variables other lanes might have contributed towards the outcome of the game, though winning lane is almost always a positive contributor towards winning games. Without additional data, it is difficult to determine the impact of item build on the outcome of the games in this particular matchup.
Something to consider as well is how itemization for the same matchup changes per individual game; though we have no way of knowing how each of the games from the small set of lethality into Renekton went, we can speculate that maybe due to the team's investment(ex. jg sup covering top) or skill differences(ex. d4 renek vs gm Ambessa top) some of the lethality games are played from spots where players have accumulated an unusual lead(i.e. "oh Renekton's 0/5 by 7 min and I'm up 3 lvls, I'm going lethality"). Those games could be considered outliers, bringing down the sample size of data points usable from the set of lethality games. This might be applicable in inverse to the eclipse games where enemy camping top or opposite skill difference creates an unusual disadvantage even in even/winning lanes, etc. However without empirical data showing gold differences @ 10 min / item build times, we cannot confirm this theory without circular reasoning.
TL;DR: The difference in Eclipse vs. Lethality win rates overall is likely driven by item selection acting as a proxy for lane state (losing ~ eclipse vs. winning ~ lethality), rather than build efficiency alone. Difference in Eclipse vs Lethality winrates in Renek vs Ambessa is from low sample size that give statistically insignificant results, meaning we do not have enough data to draw a conclusion.
