Executive Meddling: Pressure from higher-ups resulted in a huge sum of money being paid to bring Jim Steinman in to produce Hysteria, in spite of the band's protests that he was primarily a songwriter rather than a producer. Steinman later got fired and they reunited with their previous producer Robert John "Mutt" Lange.
In a way, Pete Willis, who was fired from the band just prior to Pyromania, thus not being able to share in the success of that album or its followup Hysteria. He does have some writing credit for Pyromania, however.
Troubled Production: Hysteria, partly due to Rick Allen's car accident, among other factors. Adrenalize as well.