Complex sentence: The 1939 Yankees lost the services of Gehrig early in the season; after starting the year poorly, he benched himself to end his consecutive games played streak at 2,130 and was later diagnosed with amyotrophic lateral sclerosis, which forced him to retire.
Split into simpler sentences: The 1939 Yankees lost the services of Gehrig early in the season; after starting the year poorly, he benched himself, thus ending his consecutive games played streak at 2,130. Gehrig was later diagnosed with amyotrophic lateral sclerosis, which forced him to retire.