Ok, I admit this may be a bit of a stretch; but I think the need for Perez to have 400 at bats and play all over the diamond is greatly reduced and Orf may fill the current need better. The weakness of this argument is that Orf is a 28 year old rookie without a proven major league record. I get that.
First lets look at the role required in 2018. Considering the depth in outfield it is unlikely that Perez will see very much outfield action in 2018. (In 2017 Perez played 101 games in the outfield, he was largely a back up outfielder that also played 57 games in the infield.) This leaves Perez and Villar able to cover largely the same positions in the infield. Sogard can also cover these same positions. Perhaps the greatest opportunity for Perez to get substantial at bats is as the right handed side of a second base platoon.
So the additional outfielders and the versatility of other players relieve the Brewers of the need to keep a Super Utility guy. Defensively, if a part of the team, Orf can fill in at third while Sogard or Villar provide the back up for a day off for the shortstop so Perez's infield flexibility won't be greatly missed. We then are left to compare Orf vs. Perez as the right hand side of a platoon at second base.
Although it is all in the Minors, Orf has consistently had an OBP of .350 or better. His career averages for his minor league career are .385 OBP, .401 slugging and .786 OPS. Orf is essentially the right hand hitting version of 2017 Sogard. Perez's minor league numbers were generally lower and his major league career line is .283 OBP, .388 slugging and .671 OPS. Orf also has substantially more experience playing second base.
The difficulty is that I don't believe that Perez or Villar have available minor league options. So it is a stretch to provide Orf this opportunity when in all likelihood Perez would not clear waivers to be sent to Colorado Springs. Also, it doesn't look like the Brewers are looking at Villar as a multi-position player. (I think they should.) He is basically facing a make it or break it situation at second base.
Perhaps the more likely situation is that Villar proves that he is the 2017 version of himself instead of the 2016 version and gets released during the season with Orf coming up and taking the right handed second baseman at bats at that time.