Things were not always smooth for George Kittle in his first NFL season.The tight end from Iowa, a fifth-round 49ers draft pick this past spring, injured his hamstring in training camp, then hurt a hip and an ankle in separate games during the regular season.But as the 49ers begin their offseason after a 6-10 2017 season, Kittle is one of several young players on the roster whose performance gives the Niners plenty of optimism for the future.Kittle played 15 games, caught 43 of 63 passes thrown to him for 515 yards and scored two touchdowns. His catch rate of 68.3 percent was solid. And, he had some notable big games, including the year-ending 34-13 win over the Rams in which he caught four balls for 100 yards.The analytic website Pro Football Focus graded Kittle as one of the best 49ers in that game."Kittle was a run-after-the-catch monster for the 49ers, especially in the first half," wrote PFF. "He forced four missed tackles against the Rams, matching his season total entering the game, and racked up 78 yards after the catch, more than his last eight games combined. The 49ers are riding a lot of momentum into the offseason and a big game from Kittle, even against backups, will...