Back in 1942 was the last time a unranked team shut out back-to-back teams (The North Carolina Flyers). In modern times with the high powered offenses and mixed play calling it can be difficult to shut out any team, much less a ranked one. #17 LSU didn't have a great offense, but it's defense was one of the best in the country and kept it in the game against at the time #1 Alabama. Arkansas shut them out 17-0 and got it's first SEC win since the year before. After this win, Arkansas played a much better #8 Ole Miss team that was still in mix for the College Football Playoff. This Ole Miss team had a Top 20 offense and Top 10 Defense. Arkansas forced 6 turnovers and did not allow a single point to the Rebels and won 30-0. Arkansas finished the year by allowing 59 TOTAL YARDS (2 RUSHING YARDS!) to the hated Longhorns of Texas in a 31-7 beat down. The Razorbacks also had a Top 10 defense to finish the year (allowing only 19.8 points per game in the SEC) and had some very close games against Alabama (13-14), Texas A&M (28-35 OT), and Mississippi State (10-17). In all of these games the opponent was favored by more than 2 Touchdowns and all three were in the Top 6. Hey if that isn't a great team than I don't know what is, and that is why I consider the 2014-15 Arkansas Razorbacks to be one the best, if not the best, 7-6 team of all time.
I go to Texas A&M, so I am a little biased. However, there are so many things to look at when trying to peg a "greatest team." First, I'll list what I liked in their team last year: THEIR RUNNING GAME. Both backs where splendid one-cut backs that could each put up some yards, and I liked their O-Line that backed them up. I believe the O-Line is the key to running back success, and Arkansas certainly had it last year. Their defense was pretty good (it wasn't any LandShark Ole Miss D but it was solid), I did not like their secondary which is why I think they lost most of those games. For instance, they lost to Arkansas precisely because of poor coverage. Josh Reynolds (TAMU WR) would have torn it up against that clueless secondary if he didn't drop so many passes. The lesson from that game is that TAMU, with a terrible QB (Kenny Hill) and one of the worst defenses in the country, was able to pull off a win against a team with the best running game in the country because they have a poor secondary and a bad QB.
I believe Arkansas is at the peak of their roster's cycle meaning that every five or so years, all of their lineman, RBs, etc happen to be juniors and seniors and that propels the team into random success. Arkansas' poor 2012 and 2013 seasons prove my point. Same goes for Mississippi State btw. I believe Arkansas is still on a high in their roster's cycle this coming year too, but I am not projecting them in any championship because of their lack of QB. Running games do not win championships in College Football, ask the Georgia Bulldogs.
Being better at a sport means you did said sport a lot. That means the people on that team have wasted so many hours that could actually help humanity. I value a sports person about as little as possible. So if they're the best at that sport, and that sport is what I consider to be a negative thing, then being the best at something bad makes them a bad team, to me at least.