In terms of offseason priorities, adding a starting pitcher probably wasn't at the top of the wish list that Padres' general manager Josh Byrnes and his staff compiled following the season.

But when it became apparent that free agent Josh Johnson -- a two-time All-Star who led the National League in ERA as recently as 2010 -- had sincere interest in not only playing on the West Coast but for the Padres specifically, that agenda shifted quickly.

"There's many ways to make a roster better, but we decided that if we could find a starting pitcher who could be difference-maker, we were going to go after it," Byrnes said Wednesday.

"[Johnson] has led the league in ERA and has been a dominant pitcher, and we had the opportunity to sign him. We know there's risk, but we're very excited about the upside about what he can bring."

On Wednesday, the Padres and the 29-year-old right-hander agreed to terms on a one-year deal worth $8 million, though Johnson can earn an additional $1.25 million if he makes at least 26 starts.

The deal with Johnson is the largest contract the organization has given a free-agent pitcher since Greg Maddux agreed to a one-year deal worth $10 million in November 2007.

The team also holds a club option of $4 million for 2015 if Johnson is unable to make seven starts, which is essentially risk protection given that he is coming off a rough 2013 season physically that saw him undergo surgery on Oct. 1 to remove bone spurs as well as some loose cartilage in his right elbow.

"He is coming off surgery, so this gives us some protection … in that we at least get another bite of the apple if for whatever reason that this season doesn't go as we hope," Byrnes said.

But Byrnes and Johnson -- who turns 30 on Jan. 31 -- don't anticipate any problems getting ready for the 2014 season. Johnson has already discussed his throwing program, which will begin on Dec. 1, with his new manager, Bud Black.

"We felt as though when we looked at the players we might be able to acquire, Josh's name came to the top of the list. I've seen Josh from the other side. This guy potentially for us brings a lot to the table," Black said.