Complex sentence: However, Michael Schenker proved to be very unreliable during this time period and would frequently be absent from the band's live shows, causing the Scorpions to contact Jabs at the last minute to fill in.
Split into simpler sentences: However, Michael Schenker proved to be very unreliable during this time period and would frequently be absent from the band's live shows. This caused the Scorpions to contact Jabs at the last minute to fill in.