The whole dynamic between Wilton and Tate is strange to me.
First, addressing Wilton's drop-off in the writing. Note that it began with Promised Land. I'm not sure if anyone but hardcores remember Wilton's other nickname (other than Whip)? It was Spike. Spike was essentially (at least how I remember it) what Wilton referred to as his "alter ego" after having too many beverages. On the PL tour, I believe Wilton was using guitar picks that said "Spike is Dead." I don't know this for certain, and never asked, but I always assumed it was because Wilton got some help during the time off from Empire-PL. That could be totally off base, but it's always what I assumed. And if that's true, it would explain a little why Wilton's writing dropped off significantly with PL...because he was busy with life stuff. Again, all speculation on my part.
On HITNF, he contributed even less, with just one song - Reach (a good one, with a nice riff and cool solo). So that trend continued. Q2k, everyone wrote everything together according to the credits, and that's true, they did work together, but it was mostly Kelly. Working from memory, the credits should be (according to an interview I did with Kelly 17 years ago):
(alphabetical)
Falling Down - Gray/Tate/Wilton (Wiliton's riff, Kelly's arrangement, both worked on solo)
Sacred Ground - Gray/Rockenfield/Tate
One Life - Gray/Tate
When the Rain Comes... - Tate/Wilton
How Could I? - Gray/Tate
Beside You - Gray/Tate
Liquid Sky - Gray/Rockenfield/Tate
Breakdown - Gray/Jackson/Rockenfield/Tate
Burning Man - Gray/Rockenfield/Tate/Wilton
Wot Kinda Man - Gray/Tate
Right Side of My Mind - Gray/Tate/Wilton
>>>>>So clearly, there was a unity on Q2k. A sense of "hey, we can do this without Chris." But come the time of Tribe, it really appears Wilton and Tate just butted heads completely. I remember my interview with Wilton where he blasted Tate for the direction early on (before Chris got involved), and the whole spat the summer of 2002 with Geoff calling the guys all "dysfunctional" on radio. But once the album finally got released, Geoff was complimentary of Wilton, saying that he had a big hand in the writing of them (which he did). So I'm guessing at that point they reconciled a bit. But once that tour cycle ended, it was obvious from that point forward that Tate was not interested in what Wilton was doing (as evident from the Mindcrime II - Dedicated to Chaos era).
Just a very strange dynamic. Slater's commentary in the podcast about the guys, at least from my two years or so of being much more involved with them was pretty spot-on. They all seem cool when you're talking to them, and when they need something from you, they'll be your best friend. But the moment they don't - its like you don't exist, and they become completely different. I can tell you from experiencing that from them first-hand, Slater is absolutely right about that.
They are just a really strange band, and without DeGarmo to bring the best out in all of them, and bridge together their divergent creative paths, they just miss the plot most of the time.
Even with the current era of QR with Todd and Parker in the band. I remember in spring 2013, backstage, they were talking about having to go back and remember the credits of who wrote what for the record. One thing that stood out was Todd saying at some point (I forget which song) that people wanted credit for things they didn't do. For example, Eddie is credited for doing background vocals on the self-titled. Eddie didn't sing a note. Todd did them all. But Eddie wanted credit. Todd didn't think it was a problem, because Eddie was going to be singing background on those songs anyway, so Eddie got a "background vocals" credit on the record.
But from a writing perspective -- Wilton is credited on Where Dreams Go to Die. But Wilton only slightly tweaked something on that song. On Open Road, Wilton didn't write the tune - Todd did. But Wilton wrote a solo and took Todd's solo, and slapped it on the end (so he slightly arranged the last bit of the song). And so Wilton took a credit on that tune.
However, I'm not slighting Wilton. I'm saying all that to support Slater's description of Michael, and why, perhaps, Tate didn't connect with him. Look at songs such as Redemption, Vindication, and Don't Look Back. Those songs are crafted around Wilton's major riffs. I'd bet my last dollar that Rockenfield and La Torre had a heavy hand arranging the songs around those riffs.
Michael is a killer player, and one of my favorite guitarists, and he writes great metal riffs. But if you look at his style of songwriting, you'll see most of the songs that are listed as Tate/Wilton are mostly metal riff heavy, with a more simple arrangement. So I can totally see what Slater was saying in the podcast, how Tate likely struggled at times to write over what Wilton was doing. Because a great riff (like the one in Murderer), by itself, doesn't lend itself to write lyrics on. The song needs to be fleshed out. And that's where I think at times, the disconnect between those two creatively was. QR always needed another guy to flesh out what Wilton and the other guys were trying to do, and make it inspiring to Tate to write over and gravitate to.
And perhaps, at the start of the Tateryche/Slateryche era, Tate simply didn't want to do that any longer because it was a big headache. I'm not saying it was right (I happen to think Tate had a responsibility to work on the music composed by the band, not other people), but I am saying that how Slater categorized everything is probably pretty spot-on, based on observation of the catalog of music, and the limited information on the creative side of the band that I know of and partially witnessed.
On Condition Human, Michael had a lot of credits. The writing chemistry between Wilton and La Torre is really good, because Wilton had some great riffs, and La Torre, being a musician, probably was able to take those riffs (in a DeGarmo/Gray/Slater mold) and expand on whatever initial demo arrangement Wilton put together. Tate was never able to really do that with Michael alone, because Tate isn't a music writer -- La Torre is. And La Torre is also into very heavy music like Michael. So there is a connection there, that didn't exist with Tate.
That said, like Slater said, keep in mind that Geoff is the one that championed MIchael's riff in Murderer -- Geoff likes heavy guitar riffs. But he's not able to pick up the guitar and take some great riffs and link them into a melodic song. He's not music writer in that sense. That's why Chris was vital, because he bridged that gap. La Torre now, along with Jackson (and Rockenfield, but now probably no longer) are able to fill that role, and that's why you see Michael being more prolific -- because the singer in the band is able to help craft (musically) the melodic passages needed.
Creatively, that's where Wilton and Tate had difficulty getting on the same page, and why Chris was so vital in that chemistry.