Had everything gone according to plan yesterday, David Ortiz would have taken a few swings in the batting cage for the first time in almost two weeks.

But nothing about this spring has been as Ortiz intended.

By now, though, with the hobbled slugger already bound for the disabled list because of two aching heels, the Red Sox’ most pressing concern isn’t only his setback-filled rehabilitation that has been dragging on for eight months. They also must figure out how best to patch the Big Papi-sized void in the middle of their order.

And it goes beyond just trying to replace Ortiz’ production, a mission impossible given the paucity of pure sluggers on the roster. It also involves finding players who are comfortable with being a designated hitter, a role that isn’t nearly as simple as it sounds.

While DHs don’t have to worry about playing defense, they also don’t have the opportunity to cast aside a difficult at-bat by picking up a mitt and fielding a position. Instead they’re left to stew on the bench, scan video in the clubhouse or play whatever mind games are required to prepare them for their next trip to the plate.

“It’s different, 100 percent,” Red Sox left fielder Jonny Gomes said. “It’s funny when you see guys that are first-time-ever DHs just throwing in the towel. I’ve seen guys take an 0-for-4 and throw up their arms and say, ‘Can’t do it.’ It’s definitely not for everyone.”

In recent years, many American League teams have taken a new approach to the DH. Rather than employing a full-time designated hitter, they rotate players through the position, using it as an opportunity to give them periodic rest from playing defense.

But because Ortiz has remained productive through his mid-30s, averaging 27 homers, 89 RBI and a .900 on-base plus slugging percentage over the past five seasons, the Red Sox have stuck with the traditional DH. As a result, Gomes is the only other player on the roster with more than 50 career starts as a DH.