How it works
After doing a Best in Bags or Best in Slot optimization, the Gear Optimizer will now show you a new "Customize" section (on the right with a wider screen, below the results on a narrow screen) with alternative Legendary item configurations that are close in value to the chosen solution. You can click on one of the alternatives to easily lock it in and use it instead of the solution that was automatically selected.
Note on Best in Slot
Due to technical reasons with Best in Slot, after locking in a legendary combo (or locking in any other item), the Customize list might be empty or only show a small number of results. This is because once you lock stuff in, the optimizer no longer searches combinations that your locks wouldn't allow. You need to unlock everything again to get the full list.
This limitation is not in place for Best in Bags -- the full list of alternatives will always show. We can do this because your inventory is a much smaller search space than all available items.
Why did we add this feature?
We think that this is one of the most important features that we have added this expansion -- it is a big step towards making our gearing philosophy both useful and accessible to all players.
Anyone who says they can look at all of your gear and find the single best combinations with zero error... is lying. Nobody has a model of the game that is good enough, or knows with enough detail how you personally play the game to guarantee a solution. So it is doing you a disservice to not show and quantify other viable alternatives.
And this isn't just about "accuracy" -- let's say for the sake of argument that we know with perfect accuracy that legendary combo A will, on average, perform up to 3% better than combo B. We still think it is important to show you that combo B is really close to combo A. Then you can feel confident that if there is some less measurable difference between those combinations, both are still very viable for top-level play. You can be confident experimenting with either.
All of the alternative legendary combos that we show are viable -- if there is something about how you like to play the game that makes one of them feel better to you than what we automatically choose... use it! Doing so is not "wrong" or "sub-optimal". Our theoretical model shows that it will be close enough to optimal that other factors may make it slightly better or worse for any given individual.