After falling flat on its face with 2013's Supercollider, Megadeth rebounded hard in 2016 with Dystopia. The album was the first to feature Angra guitarist Kiko Loureiro, and the only Megadeth album to feature Lamb Of God drummer Chris Adler.
Adler was hired as a studio guy after the departure of Shawn Drover in 2014, and now bassist Dave Ellefson is crediting Adler as a pretty big part of Dystopia's sound. To be fair, Ellefson also credits Loureiro as being a good compliment to Dave Mustaine's playing and writing style.
We've done a lot of different things in our career. We're a band that can write really intricate riffs, we're a band who can write great choruses and hooks. I think the trick with Dystopia was sort of fine tuning it and bringing all those elements together, because you can't be the band you were on your debut record, and you're not even gonna be the band you were on your last record, because life moves forward and developments happen. And Chris Adler was a big part of helping Dystopia get focused. And Kiko coming in brought that… Megadeth's always had two… Dave and then this other juxtaposed guitar player, and I think Kiko really complemented that well… And live, Kiko's an incredible performer as well.
I think it'd be really interesting for Ellefson to elaborate on Adler's contribute more. Adler isn't credited as a songwriter for any of the songs, though apparently his role was pretty substantial.