Complex sentence: Once again, Denver's defense forced a "three and out" for a fourth consecutive time, and it was back to back "six and outs" by Denver's defense beginning the second half to keep the score tied at 17--17.
Split into simpler sentences: Once again, Denver's defense forced a "three and out" for a fourth consecutive time. Marking back to back "six and outs" by Denver's defense to begin the second half to keep the score tied at 17--17.