Complex sentence: However, not all the new agents were rookies; experienced hands arriving included Thomas Fosmire, Tony Poe, Pat Landry, Joe Hudachek, Jack Shirley, and William Young.
Split into simpler sentences: However, not all the new agents were rookies. Experienced hands arriving included Thomas Fosmire, Tony Poe, Pat Landry, Joe Hudachek, Jack Shirley, and William Young.