Allow me to revitalize this thread.
I am a Dream Theater fan, and have spent hours contemplating John Myung's skills and role.
I have come to the conclusion that he is a robot. He can technically play anything that anyone tells him to play, but he does not have good ideas to actually contribute to the the music.
He can play simply, or match the other guys' riffs, but usually he is just along for the ride, and he's not worth paying attention to even when he's audible.
He practices obsessively for hours and hours. He practices while the other guys have fun, even since the Majesty days. But why?
Why would someone spend so much time practicing when they don't create music? He sometimes taps; I've never seen him slap; he played his share of harmonics back in the 90s.I would expect one who practices six hours a day to have a mastery of extended techniques, and be a prolific writer.
He could at least play a harmony line once in a while! Would that be so hard, to play a third above Petrucci instead of playing another unison?
Many of his solos are based around patterns. Look at Metropolis: F# in three different octaves, and one B just for fun. He plays it multiple times, then moves it up without variation. What a glorious, innovative, and moving solo. Erotomania and Dance of Eternity: Half of these solos are just patterns that he probably played thousands of times before forming Majesty.
The only time I can totally hear him on their newest album is during one of te cool guitar-keyboard unison lines in the intro of The Count of Tuscany. Rocking the root whole notes. And when the key changes come a while later, you can hear him playing root eighth notes. This is one of the big progressive bassists? The heir to Steve Harris, Geddy Lee, Cliff Burton? On When Day and Dream Unite he was audible, and he sometimes played really cool stuff.
It's one thing to serve the song. It's another to put little thought into your lines, copy your bandmates, and allow yourself to be buried in the mix album after album.
He's a great technical player and I admire his dedication- but what happened to his spirit of innovation or creativity? He's not setting a good example.
The drummer is Neil Peart incarnate, and root boy here chugs along down below. 
john myung is an excellent bassist and a nice guy too...i would love to hear those guys live again. without vocals though. that guy is pretty horrible live.
. I can't really see where much slapping would fit into DT's music anyway. But slapping sure is a lot of fun, so any bassist should learn the technique for the fun of it.
