Complex sentence: After Marlin Jackson suffered an Achilles tendon rupture during organized team activities, Allen was named the starting free safety going into training camp, replacing the 2009 starter, Sean Jones (safety).
Split into simpler sentences: After Marlin Jackson suffered an Achilles tendon rupture during organized team activities, Allen was named the starting free safety going into training camp. He replaced the 2009 starter, Sean Jones (safety).