There are several ways to identify which engines are performing / not performing. I thought that I would share my method in this post.
I wrote an Excel VBA tool to compare submitted vs verified URLs. The output can be used to identify which engines that performed well. Then you can focus on them to improve your LPM. However I'm not sure if you guys are interested with this? The macro is not "very easy" to use as you need to tell it where the "site_list-success" and "site_list-verify" folders are located prior to running it. Below is a screenshot of the outcome.
The macro basically loads the files within the above folders and count the URLs. You could then compare between submitted vs verified and determine which ones are performing well or not.
Let me know if you guys are interested and I can write more details on how to use the tool and share the macro.