Mozilla started from Netscape which had already lost a lot of market share before surging back. Browsers are free which makes it fairly easy to gain or lose marker share. All it takes is the current leader to stumble and people quickly jump ship. I suspect it's easer to catch up as you have some goal to target.
Mozilla was spun out from Netscape but it itself is not Netscape as Netscape was aquired by AOL. 89% is still a far cry from anything Firefox has managed.
Either way you look at it Netscape did not bounce back.
