This is going to be very long, so be prepared for a lot of reading.
I personally do not find the current UFC Middleweight Division to be weak, but I hear arguments that attempt to prove that the division is indeed a weak division. I would like to examine some of these arguments and offer commentary about these arguments.
1. Most Top UFC Middleweights are Washouts from Light Heavyweight
There a couple issues with this argument. It is not uncommon especially in this day and age of weight cutting where fighters that start at a higher weight division tend to cut down to the lowest weight division that they can. The other thing is that fighters from higher weight divisions across all weight divisions cut down and become top fighters in their new and lighter weight division. In Light Heavyweight, Rashad Evans fought as a Heavyweight on The Ultimate Fighter and its Finale and is now a top Light Heavyweight. In Welterweight, Jon Fitch used to fight as high as Light Heavyweight and was for the longest time the consensus number two Welterweight. Martin Kampmann was also a Middleweight that is doing very well at Welterweight. Nate Marquardt is making the cut to Welterweight as well. Josh Koscheck has fought at Middleweight as well. In Lightweight, Sean Sherk fought as a Welterweight and became Lightweight Champion. Kenny Florian fought as high as Middleweight and also at Welterweight, but he found most of his success as a Lightweight. A couple top featherweights are former Lightweights. Jose Aldo, Dustin Poirier, Bart Palaszewski , Pat Curran, fought at Lightweight and cut to Featherweight. Mike Thomas Brown was a mid-tier Lightweight and became WEC Featherweight Champion. UFC Bantamweight Champion Dominick Cruz was a Featherweight. The other thing to look at is while there are former Light Heavyweights who cut to Middleweight and became top Middleweights, there are many such as Eric Schafer, Steve Cantwell, Tom Lawlor, Jason Lambert, and others who washed out in both weight divisions. It is not like every Light Heavyweight who cuts to Middleweight will be a top ten-to-fifteen Middleweight.
One other thing to look for as well is just the simple fact that certain fighters simply fight better at certain weight classes. Dan Henderson, for example, can cut to Middleweight, but he is seeing more success at Light Heavyweight. Fitness, speed, strength, and general comfort may be found in Middleweight rather than Light Heavyweight. From a physical standpoint, Tim Boetsch looks much more fit as a Middleweight than as a Light Heavyweight.
2. Mark Munoz
Mark Munoz has been strong evidence for many who argue that the Middleweight Division is a weak division. These MMA fans argue that the UFC Middleweight Division must be weak because a fighter who got head kicked KO'd by Matt Hamill, of all fighters, dropped down to Middleweight and is now a top ten fighter. The problem with the Munoz argument is simply that his loss to Hamill does not tell the whole story. When Munoz fought Hamill, Munoz’s record was 5-0. Matt Hamill's record was 6-2 with seven fights up to that point being in the UFC. So, Hamill had more fights in the UFC than Munoz had professional MMA bouts. Also, while Munoz is still a bit raw in his approach when fighting, he was extremely raw and green when he fought Matt Hamill. Hamill, while not a great fighter, was a pretty established mid-tier by that fight having fought fighters like Rich Franklin, Tim Boetsch, and Michael Bisping. For Munoz, it was also his first fight in the UFC, which could lead to "Octagon Jitters." He also just looks much more fit as a Middleweight than as a Light Heavyweight.
As a Middleweight, Munoz was brought up very well. While he is still rough around the edges in his fights, there is improvement with him. Also, his training has been getting much stronger with his gym, Reign MMA, and training with Black House fighters like Anderson Silva, the Nogueiras, and others.
3. The UFC Middleweight Division has a History of being a Weak Division
I'm going to be honest, but I never found how this argument is pertinent or relevant to what the division is now. Yes, the first UFC Middleweight Champion is Dave Menne, and fighters that are not that good like Evan Tanner (bless his soul) held the Title, but I just do not see how that has any bearing to what the division is now. The UFC Middleweight Division has around 47 fighters. The top ten fighters of the division are Anderson Silva, Chael Sonnen, Yushin Okami, Mark Munoz, Vitor Belfort, Michael Bisping, Luke Rockhold, Chris Weidman, Brian Stann, and Hector Lombard. according to the most recent USA Today/SB Nation Consensus Rankings. Removing Rockhold and Lombard, and just going with UFC fighters, Demian Maia and Rousimar Palhares would be up there (Tim Boetsch is not ranked higher yet as this was made before the Okami fight).There are up-and-comers in the division such as Chris Weidman, Alan Belcher, Brian Stann and Rousimar Palhares. There are prospects in the division like Andrew Craig, Brad Tavares, Clifford Starks, Ronny Markes, and Costa Philippou. The division has a pretty established mid-and-lower tier of varying levels of ability and skill. Also, having around 47 fighters in the division shows that there is no shortage of quantity in the Middleweight Division either. While the division may have started out weak, it progressively became stronger and is now a seemingly solid weight division.
4. UFC Middleweights Who Fight for the Title do not Have Long Win Streaks
My problem with this argument is simply that this is not mutually exclusive to the UFC Middleweight Division, but it applies to every weight division in the UFC. The way that Title shots usually work is that a fighter gets a bit of a win streak, usually three or more consecutive victories, and in one or more of those victories is a top ten opponent. Middleweight follows that formula. For an example in another weight class, Benson Henderson at Lightweight defeated Mark Bocek, Jim Miller, and Clay Guida in a row to get a Title shot against Frankie Edgar. He lost to Anthony Pettis in the WEC before the win streak. Now in Middleweight, Chael Sonnen defeated Dan Miller, Yushin Okami, and Nate Marquardt to get a Title shot against Anderson Silva. Before that win streak, Sonnen lost to Demian Maia. Chael Sonnen did not do anything different to get a Title shot than what Benson Henderson did. While there are instances like Dan Henderson getting a Title shot coming off a loss to Rampage Jackson, or Demian Maia getting a Title shot filling in for Belfort but only beating Dan Miller and not having a real consecutive win streak, for the most part, most Middleweight Title contenders have a win streak before challenging for the Title. There are extraneous cases in other weight divisions as well, and not just Middleweight. Also, this argument does not look at level of competition for those fighters who did have a long win steak and fought for a Title. Jon Fitch, for example, in the UFC defeated Larson, Burkman, Alves, Hironaka, Fioravanti, Diego Sanchez, and Chris Wilson before fighting GSP. What stands out is that only one of those fighters was a top ten opponent during that time, Diego Sanchez (Alves was not ranked highly during that time). Granted, there are fighters like Jake Shields and Thiago Alves who beat multiple top ten opponents before getting a Title shot, but that is not always the case for Title challengers with long win streaks. I think that it is safe to say that if the UFC gave these top Middleweights consecutive mid-tier fighters (not up-and-comers or good prospects, but just established mid-tiers), that they could get an extended win streak as many of these top Middleweights have proven that they can consistently beat mid-level fighters.
5. The Challengers for Anderson Silva’s UFC Middleweight Championship were only Sub-Par Fighters
The obvious problem with this argument is that it is a complete blanket statement with no real evidence behind it. There is simply a lack of any real basis for this argument except for the argument that the Middleweight division is thin or weak, but that in itself is a blanket statement. I will try to challenge it nonetheless. Just looking at stylistic matchups and comparing Anderson Silva’s competition to GSP’s, I actually see many similarities in opposition from a stylistic standpoint. With strikers, GSP fought Dan Hardy and Thiago Alves. Hardy would be comparable to Patrick Cote. Alves would be comparable to Vitor Belfort just in being known as high level strikers, not necessarily in their style of striking. With wrestlers, GSP fought Josh Koscheck, Jon Fitch, and Matt Hughes. Dan Henderson is a strong wrestler with a powerful overhand right, so I would compare him to Koscheck. From an offensive standpoint, Sonnen and Fitch are comparable; it’s just that defensively they are not comparable. Matt Hughes is admittedly a bit tougher, but I would go with someone like Marquardt or Okami as someone comparable, but even I will admit that I’m stretching that. With BJJ practitioners, GSP fought Jake Shields and Matt Serra (even though Serra TKO’d him in their first bout). Maia would be comparable to Shields, and Lutter or Leites would be comparable to Serra (as far as BJJ goes). BJ Penn is probably the only fighter I cannot find a comparison for. The point is that I just do not see how Anderson Silva’s competition was sub-par. He is clearly fighting high level fighters with various stylistic challenges.
One other thing that I noticed with MMA fans who argue that the Middleweight Division is thin or weak is that they act as if their arguments are exclusive to the Middleweight Division. I have pointed out that in all weight divisions, fighters from a higher weight division cut down and become top fighters in their new weight division, and some don’t. A lack of long and extended winning streaks to get a Title shot is not exclusive to the Middleweight Division, and even then, Middleweights in general do not do anything differently to get a Title shot than what other fighters do to get one in other weight divisions. I have heard arguments that top Middleweights have distinct weaknesses like Sonnen having bad BJJ defense, but this argument applies across the board, and not just with Middleweight.
I will concede that Middleweight is not as stacked or deep as Welterweight or Lightweight. Just because those two divisions, in my opinion, are stronger than Middleweight does not mean that Middleweight is a weak weight division. Going with definitions though, I would not say that Middleweight is “stacked” as Welterweight and Lightweight are defined as “stacked,” but it is not “weak” either. I would define it somewhere in the middle and call it “solid.” There is nothing about weighing 185 pounds that automatically makes a fighter a weaker fighter compared to fighters in other weight classes. Overall, I just do not see how Middleweight can be considered a thin or weak division, especially with the evidence provided.