One Bills' Undrafted Rookie With Most Realistic Path to 53-Man Roster Spot

One needs to look no further than Buffalo Bills' defensive coordinator Jim Leonhard to see what's possible for an undrafted rookie in the NFL.

In 2005, Leonhard made Buffalo's 53-man roster after going undrafted out of Wisconsin. The high-motor safety went on to play 10 seasons in the league before transitioning to coaching.

As for current Bills' players, offensive lineman Alec Anderson, linebacker Joe Andreessen and wide receiver Tyrell Shavers all signed undrafted free agent contracts out of college.

Sep 15, 2013; Orchard Park, NY, USA; Buffalo Bills defensive back Jim Leonhard (35) during a game against the Carolina Panthers at Ralph Wilson Stadium. | Timothy T. Ludwig-Imagn Images

This week, Buffalo announced the addition of 12 undrafted rookies with some naturally holding better survival odds than others.

While we wrote about Youngstown State wide receiver Max Tomczak's potential to stick around, the Bills' UDFA rookie with the best chance of making the team is most likely Wisconsin fullback Jackson Acker, and here's why.

Completely open FB competition

There's no incumbent fullback on the Bills' 90-man roster following Reggie Gilliam's departure in free agency, meaning there's a wide open competition for the role.

While Buffalo isn't required to carry a fullback on the 53-man roster, first-year head coach Joe Brady seems to have a fondness for position and the extra possibilities it creates for the offense. For the record, Gilliam logged 235 offensive snaps in 2025. Therefore, let's assume the Bills will at least employ a hybrid back of sorts, and Acker has a good chance to fill the need.

Sep 7, 2024; Madison, Wisconsin, USA; South Dakota Coyotes defensive back Teven McKelvey (3) grabs the facemask of Wisconsin Badgers running back Jackson Acker (34) | Jeff Hanisch-Imagn Images

Currently, Acker's only challenger is the recently-signed Ben VanSumeren. The former Philadelphia Eagles' linebacker-turned-fullback has not played since tearing his patella tendon in the 2025 season opener.

It's also worth noting that Brady publicly appreciated Gilliam's ability to run routes out of the backfield, suggesting it made the Bills' offense tougher to defend.

Although Acker wasn't primarily a college tight end like Gilliam, who was also an undrafted signee, the Wisconsin fullback flashed receiving ability throughout his career to the tune of 37 receptions for 276 yards and three touchdowns.

Acker's credentials and connections

The 6-foot-1 Acker became Wisconsin's primary fullback during the 2022 season when the aforementioned Leonhard was serving as Badgers' interim head coach. Leonhard was defensive coordinator when Acker redshirted in 2021.

One has to think Acker's familiarity with a prominent member of the Bills' coaching staff is a key reason for choosing to sign with Buffalo after going undrafted.

Acker made 50 career appearances for Wisconsin, including 14 starts mostly at fullback. He also saw occasional snaps at running back and tight end. Averaging 4.4 yards per carry, Acker rushed for 415 yards and three touchdowns for the Badgers.

Recording a 6.63 Relative Athletic Score (RAS), based upon his pre-draft testing, Acker ranks in the top 35 percent of fullback prospects since 1987.

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