Complex sentence: Since March 2014 he is the coach of Charlton Athletic.subject to a slightly mixed reception due to the circumstances in which he was introduced as manager, following Sir Chris Powell's sacking.
Split into simpler sentences: Since March 2014 he is the coach of Charlton Athletic. On arrival, he was subject to a slightly mixed reception due to the circumstances in which he was introduced as manager, following Sir Chris Powell's sacking.