During the band's early days, Mustaine was the rhythm guitarist, while Chris Poland played lead. Although Poland performed only on Megadeth's first two albums, music journalists Pete Prown and Harvey P. Newquist credit him with making the music more colorful because of his jazz influences. According to former "Metal Maniacs" editor Jeff Wagner, the band's songwriting techniques peaked with the fourth album, "Rust in Peace", which he described as a "flurry of precision and fluidity, making good on Megadeth's claim to being the world's state-of-the-art speed metal band". Musicologist Glenn Pillsbury stated the guitar work on the album was a mixture of Mustaine's "controlled chaos" and the "technical brilliance" of Marty Friedman. Studio efforts released in the mid- and late 1990s featured songs with compact structures and less complicated riffing.