ST. LOUIS – Remember, when the question going into the season was whether Colin Kaepernick and Vernon Davis could have on-field chemistry?Now, three games into the season, it is apparent Kaepernick absolutely needs Davis on the field. The tight end missed his first game since 2007 Sunday in a loss against the Colts because of a hamstring injury. He will be a game-time decision Thursday night against the Rams.According to ESPN Stats & Information, Kaepernick has completed just half of his pass attempts in his career with Davis off the field and 47.