What happened: The San Francisco 49ers announced the passing of former linebacker Aldon Smith at age 36. Smith was a focal point of the dominant Jim Harbaugh era defenses and set numerous league records during his historic start to his career.

Why it matters: Smith's 19.5 sacks in 2012 is still the official While the team has seen legendary defenders across different eras, Smith's unmatched defensive peak from 2011 to 2013 provided a ceiling that few pass rushers in NFL history have ever touched.