By Ryan Kartje
LOS ANGELES — Ninety minutes before the Rams new offense made its preseason debut against the Cowboys, its new top receiver stood in the tunnel of the Coliseum in street clothes. Sammy Watkins was reeling from news of his trade a day earlier. He’d just arrived in Los Angeles from Buffalo, whisked from the airport to the stadium. For Watkins, it was a whirlwind. For the Rams, his arrival was an adrenaline shot for a Rams passing game still in desperate need of one.