Complex sentence: St Kilda made a great start to their 1999 premiership season after progressing to the top 4 in Round 10, however, this form soon and disappeared and by the seasons conclusion they would finish 10th on the ladder.
Split into simpler sentences: St Kilda made a good start to the 1999 premiership season after progressing to the top four in Round 10. Their form, however, then faded and by the season's end conclusion they would finish 10th on the ladder.