After a six-month break, which Dickinson mostly spent practising fencing, Iron Maiden began writing their next album, Somewhere in Time. Dickinson was disappointed with the effort as he felt that the band needed a more dramatic stylistic departure from past records to remain relevant, despite its introduction of synthesised bass and guitars. He has no writing credits on the release, as his material, based on his own suggestion that the album should be more acoustic-focused, was rejected by the rest of the band. Steve Harris, on the other hand, stated that his material was rejected because it was not good enough, and that Dickinson "was probably more burnt out than anyone at the end of the last tour".  After a subsequent tour, Iron Maiden started working on their next studio effort, Seventh Son of a Seventh Son, which featured more progressive rock elements than the band's previous records. Although it became their second release to top the UK charts, it was also Dickinson's first album with the band that did not achieve platinum status in the US. Unlike Somewhere in Time, Dickinson was much more enthusiastic about this album due to its concept and has several song-writing credits. After the following tour in 1988, the band decided to take a year off.  During the next album's writing stage, Adrian Smith left Iron Maiden, and was replaced by Janick Gers. Iron Maiden's eighth studio release, 1990's No Prayer for the Dying, had a raw sound that, according to AllMusic, did not "hold up well" compared to past efforts, as it was recorded in a barn which Steve Harris owned, with a mobile studio owned by the Rolling Stones. The record featured Dickinson's "Bring Your Daughter... to the Slaughter", originally composed for a film soundtrack, which despite receiving a Golden Raspberry Award for worst original song in 1989, became the band's first and only single to top the UK Singles Chart. By 1992, Harris had converted his barn into a proper studio, and the new album, Fear of the Dark, was recorded there, resulting in a better overall sound than No Prayer for the Dying, although Dickinson still claims it had limitations due to its size.  After the Fear of the Dark Tour, Dickinson decided to leave Iron Maiden to concentrate on his solo career. At that point the band had already booked a following tour in 1993, which Dickinson did not enjoy. Throughout the tour, Dickinson drew a lot of criticism from his bandmates, with Steve Harris in particular saying, "I really wanted to kill him." According to Harris, Dickinson would only perform when the press was there, whereas at other concerts he would only mumble his way through songs. Dickinson has since denied the accusations that he was deliberately under-performing, arguing that it was impossible to give a decent performance some nights because of the atmosphere. His last performance with the band was filmed by the BBC at Pinewood Studios and released as a live video, entitled Raising Hell.

Answer this question "Did he mumble thru his songs?" by extracting the answer from the text above.
Dickinson has since denied the accusations that he was deliberately under-performing, arguing that it was impossible to give a decent performance some nights because of the atmosphere.