Minnesota Vikings head coach Mike Zimmer made it clear following the 2015 season that improving the offensive line was a priority. And while the Vikings offensive line paved the way for running back Adrian Peterson to lead the NFL in rushing yards, they struggled to protect quarterback Teddy Bridgewater.

Bridgewater was sacked 44 times during the 2015 season, which tied for the sixth-most in the NFL. The Vikings front office is expected to make some moves to bolster their offensive line as they look to protect their young quarterback, and have reportedly already lured one upgrade through free agency.

Former San Francisco 49ers guard and impending free agent Alex Boone is expected to sign with the Vikings at the outset of the new league year. If the deal comes to pass as expected, look for Boone to have an immediate impact next season. The undrafted two-time Pro Bowl offensive lineman turns 29 years old this offseason, and started 13 Niners games last season before suffering a knee injury.

The Vikings hired Tony Sparano as their offensive line coach back in January, and Minnesota is clearly looking to rebuild Sparano's unit with a focus on pass protection. The Vikings were nearly dead last in the NFL in terms of passing yards per game, and are likely hoping the addition of Sparano and Boone is just the start of better offensive line play in Minnesota. Boone and Sparano were both part of the 49ers organization last season, but the new Vikings offensive line coach was a tight ends position coach in San Francisco.

Boone is likely just the first move Minnesota is making at the position this offseason, though it would be surprising if the team used a first or second round pick to target an offensive lineman in the 2016 NFL Draft.

"We've got to do better," Zimmer said following the 2015 season. "I think we need to compete at that position. I think guys need to come in and compete whether it's (John) Sullivan or (Phil) Loadholt or (Matt) Kalil or whoever it is."

Even with Boone's addition question marks still surround the group, especially at the tackle spots where Matt Kalil and Phil Loadholt are both entering the final year of their contracts.

In other free agency news, the Vikings have also re-signed defensive tackle Kenrick Ellis, and have reportedly agreed to terms with former Lions linebacker Travis Lewis.

Minnesota won the NFC North for this first time since 2009 this past season, and the Vikings are looking to continue their ascent and build a consistent contender through free agency and in the upcoming draft.