In what ways do you specifically mean "catch up"? Gartner has AppDynamics only slightly ahead of IBM in its PeerInsights:
https://www.gartner.com/reviews/market/apm/compare/appdynamics-vs-ibm
In my experience, all three of the products are great, and we've seen customers succeed and fail with all of them for various reasons.
Frank Tate
www.gulfsoft.com