The Oakland Raiders and St. Louis Rams met in a preseason opener on Friday, and despite the main storyline centering on the two clubs' potential return to Los Angeles, there was plenty of focus on depth. The Raiders cruised to an 18-3 victory, but more importantly, new head coach Jack Del Rio received some encouraging signs on the passing game from multiple players.

Perhaps the most contentious position for the Raiders is at wide receiver. The unit was effective against St. Louis, catching 19 passes for 171 yards and the game's only two touchdowns. It's a step in the right direction, as the offense makes the transition under new coordinator Bill Musgrave. What seemed to be a glaring weak spot for the Raiders last season might be a bright spot going forward.

In the offseason, Oakland signed Michael Crabtree to a one-year contract, and also used the No. 4 overall pick in the draft on Amari Cooper. Against St. Louis, Crabtree and Cooper combined for five receptions and 37 yards, and Cooper was even used in an end-around for three yards. Overall, it was a strong effort for the newcomers. With a bolstered No. 1 and No. 2 option, and with Andre Holmes returning, second-year quarterback Derek Carr may have big playmaking options to significantly boost Oakland from a disappointing air attack that finished 26th in passing yards (204.7) to go along with 22 touchdowns in 2014.

More help is also on the way, with Rod Streater returning from a season-ending foot injury that limited him to just three games. Streater will look to reestablish himself as the same explosive player who finished with 888 receiving yards in 2013. He had previously missed 11 practices this year due to illness, and now joins an upgraded unit that also includes Brice Butler among seven others trying to make the 53-man roster. 

"It's exciting," Streater said. "It pushes me harder to come back. It's exciting to see them work hard on offense and be successful. It's a good group of receivers."

How Streater, Holmes and Butler perform in preseason might be a strong indicator of who gets looks when Carr isn't throwing to Cooper and Crabtree. Butler might be the most intriguing player in the group, as a former high school standout who was also stuck in a crowded receiving corps at USC before transferring to San Diego State for his senior year. Entering his third season, Butler had 21 receptions and two touchdowns with Oakland in 2014, and looked sharp against the Rams, leading all receivers with six receptions for 57 yards and a touchdown.

In the first quarter, Carr even found Kenbrell Thompkins on a slant, perhaps adding even more competition to an already crowded unit. Thompkins was targeted 47 times in 2014 as a member of the Raiders and the New England Patriots. The 27-year-old had a solid rookie campaign with the Patriots in 2013 when he finished with 466 receiving yards to go along with four touchdowns.

Outside of the receivers, the Raiders may also see an uptick in receiving yards at tight end. Musgrave began Friday's game with a two tight-end set, though leading tight-end target Mychal Rivera wasn't thrown a pass.

Clive Walford, the team's third-round pick in 2015, caught 44 passes for 671 yards and 7 touchdowns at the University of Miami in 2014. Against the Rams, he finished with two receptions for 28 yards despite missing most of camp with an undisclosed injury.