Eyebrows raised in March 2017 when San Francisco signed Kyle Juszczyk to a four-year, $21 million contract, a record for a fullback. Sure, he was effective for Baltimore with seasons of 19, 41, 37 and 33 catches. But the average value of $5.25 million was miles ahead of what was projected to be last year’s highest salary cap hit for a fullback ($2.3 million for Kansas City’s Anthony Sherman). But flush with cap space and starting a floor-to-ceiling rebuild, the 49ers splurged and Juszczyk is now a major part of their offense. Entering Sunday’s game against the Broncos, Juszczyk has played 501 offensive snaps (62.2 percent of the 49ers’ total), most in the league for a fullback.