Matt Stainbrook is down for at least the Villanova game with what is being described as a "strain" of the medial collateral ligament. The MCL runs from the femur to the tibia on the inside of the knee is primarily used to stabilize the tibia. Generally, it is a blow to the outside of the knee that injures the MCL. Assuming there is no or only minimal tearing, Xavier's center may only be out one to two weeks. Any more significant tearing could keep Matt out for a month or more, which would obviously end his season.
If Stainbrook had to suffer an injury, there were worse times he could have had it. The Villanova game was, in all reality, unlikely to be a win either way. The layoff between that game and the start of the Big East Tournament a week later (hopefully) gives Stainbrook and the Xavier medical staff 10 full days between the time of the injury and the next game Matt would be likely to play to assess, triage, and rehab his knee in an attempt to get it ready. While it's not likely the Stain Train will regain full speed this season, there is at least a chance he gets back on the floor.
Offensively, there's no doubt that Matt was a big part of Xavier's offense this year, leading all qualifiers with an 111 ORtg on a 23.9% usage rate. He also boasts a 54.6% EFG% and was in the top 120 in the nation in OReb% (12.1%). Essentially, he's Xavier's most efficient offensive player and uses the ball more than anyone other than Semaj. His assist rate of 19.5% is third on the team and 450th in the nation, an area occupied almost solely by guards and the odd point forward.
More than just what the numbers show Stainbrook brings on the offensive end is the impact he has on creating shots for his teammates. Semaj is going to get his whenever he feels so led, but it was extremely evident without the big man in the post against Seton Hall that the rest of the team needs some help. When Matt is on the floor, defenses cannot double driving players or even rotate aggressively, because he'll pop free on the weakside for layup after layup. Teams also must double Matt in the post, because it is the rare big man who can handle him alone. That, obviously, creates space and opportunities for spot up shooters or open runs to the rim. With Xavier struggling from deep already, that spacing loss is a major issue.
Defensively, Xavier relies on Stainbrook to protect the middle of the packline defense. The fact that Xavier keeps getting torched from outside but holds opponents to the second lowest two point field goal percentage in the Big East is testament to Matt and his positioning and his best on the team 4.7% block rate. While Matt is called for his fair share of fouls, he has only fouled out of two of Xavier's 28 games that have not gone to overtime. On the defensive end, his 25 minutes per game are going to very difficult to replace.
It remains to be seen, but Xavier may have dodged a bullet here. Stainbrook's injury may be the death knell of any hopes against Nova, but if the irreplaceable big man can be back for the Big East and NCAA tournaments, the Musketeers may yet make some noise.