During training camp, there was an open competition for the San Francisco 49ers' nickel cornerback spot. It was assumed the role would be handed to Isaiah Oliver after the team signed him in free agency to replace Jimmie Ward, who moved on to the Houston Texans to play safety.
Ultimately, Oliver won the 49ers' slot cornerback job. While Ward excelled in this position last season, earning the second-highest overall Pro Football Focus grade of his career (80.6) and his second-highest coverage grade ever (76.9), there has been a noticeable drop-off with Oliver in the spot.
Although Oliver performed well over his last two seasons with the Atlanta Falcons, becoming a fan-favorite there, this season with San Francisco has seen him earn his lowest grades in three years—a 60.7 overall mark and a 61.8 coverage grade.
When targeting Oliver this season, opposing quarterbacks have posted a passer rating of 109.5, completing 87.5 percent of their passes for 271 yards, three touchdowns, and one interception. To put that into perspective, Miami Dolphins quarterback Tua Tagovailoa's passer rating of 108.8 leads the NFL.
Last season, opposing quarterbacks owned a 72.4 passer rating against Oliver, so this season has seen a significant decline in effectiveness from the veteran corner.
"The slot corner position, I think, has been a definite concern this season," Analyst Greg Cosell said Thursday morning on Bay Area radio station KNBR's "Murph and Mac" show. "And I think they knew that going in, and they settled on Oliver, who, to me, again, they're playing the guy they think is best, and they're with him every day. They're not putting out the guy they don't think is best, but I don't think Oliver, at his core, is a slot corner."
Cosell continued, "They probably feel that they don't have a great slot corner, but he's the best guy, so they're putting him out there. Because Oliver, I remember watching him in college, he's a big kid. I thought he was an outside corner, but he's now playing in the slot."
Two of the three touchdowns Oliver has surrendered this season came courtesy of Cincinnati Bengals quarterback Joe Burrow on Sunday. One featured Oliver going against wide receiver Tyler Boyd, and the other against wide receiver Ja'Marr Chase.
Cosell doesn't discredit Oliver for the Chase touchdown, noting the play was highly schemed. However, he pointed out that Oliver was simply beaten on the Boyd touchdown.
"They obviously believe, with what they have on their roster now, that he is the best slot corner, or they'd be playing someone else, but I'm not sure if he is ideally suited for that position," Cosell added.
You can listen to the entire conversation with Cosell below.
