Complex sentence: During his time at SC Freiburg, Idrissou decided he was to be more than just an average Bundesliga striker and changed clubs to Borussia Mönchengladbach in the hopes of soon playing Champions League, who, after his arrival, barely managed to stay in the league.
Split into simpler sentences: During his time at SC Freiburg, Idrissou decided he was to be more than just an average Bundesliga striker and changed clubs to Borussia Mönchengladbach in the hopes of soon playing Champions League. Mönchengladbach after his arrival, barely managed to stay in the league.