Some "good" X-Factors do literally nothing. (Proof)
Ankle Breaker and Puck On a String animation comparisons.
Linked above is a quick short I made comparing two animations that you would expect to work with the respective abilities, based on the ability descriptions. A loose puck deke with and without Ankle Breaker, and a Toe Drag with and without Puck on a String.
For the comparisons, both builds have 90 deking, the clip on the top screen has no deking Superstar or Zone abilities, and the bottom screen has the Zone ability. I then overlay them as best as I could to show that the animations start and stop at the same time.
This isn't the only test I've done, it's just the only easy to consume comparison I've created, but I went through and counted frames for multiple different animations with multiple different deking attribute breakpoints and it was consistent that the only thing that seemed to affect animation speeds was the deking attribute itself, and not the X-Factors. With Puck on a String I tested just simply moving the puck from backhand to forehand, same frame values regardless of X-Factors.
My assumption for a while now about Ankle Breaker is that if it does have an affect, it only has an affect on CPU Players, but I'm not really sure how to test that. If that is the case, it being included in World of Chel is pointless for like 99% of scenarios. As for Puck on a String, I have no idea if this does anything online or offline, in both the online Free Skate and the offline Team Practice I saw zero difference in deking speeds with or without the abilities, this seems like it's probably a bug.
One more thing I noticed about another ability some people think is really good, Shutdown, is that it doesn't seem to behave how you'd expect based on the World of Chel Description. The World of Chel Description says it helps in 1-on-1 situations. However, if you go into the Create-a-Player it says it helps defend rush chances. I tested in Free Skate and in the Pro Am (I haven't tested this in actual online games yet), but it seems how it works is that Shutdown will pretty much always activate if the puck is NOT in your Defensive Zone. Once the puck is carried into your Defensive Zone, it will continue to activate for a few seconds, regardless of how many players are near you or in your own zone, but after that few seconds pass, it doesn't seem to activate again until the puck is cleared. This leads me to think it was designed with the Create-a-player description in mind, to defend rush chances. If that's the case, a simple update of the description in World of Chel would at least fix any confusion.
Anyway, hope this helps shed some light on some things that I think might be bugs that could have gone under the radar and can lead to some tweaks and confirmation that abilities are at least helping in some way/doing something akin to what their description says.