Some assumed the Ravens would cut their longtime No. 1 cornerback to save money for other needs. Instead, they opted to maintain an enormous investment in their secondary, which for a second straight season will feature three starting-caliber outside corners. As he approaches his 31st birthday, Smith doesn’t have to prove his talent, but this has been his quietest, healthiest run-up to a season in several years. And he would surely like to play well enough to earn himself one more substantial NFL contract. Marlon Humphrey is the rising star and Brandon Carr the reliable veteran, but at his best, Smith still might be the Ravens’ best option to shadow a superstar receiver one-on-one.