Complex sentence: Band of Angels didn't make the big time but d'Abo did: in August 1966 he joined Manfred Mann ('MM'), already a chart-topping group, as replacement for Paul Jones, who was leaving to go solo.
Split into simpler sentences: Band of Angels didn't make the big time but d'Abo did. In August 1966 he joined Manfred Mann ('MM'), already a chart-topping group, as replacement for Paul Jones, who was leaving to go solo.