Flacco is by fans certainly. Birk is by the media and(analyists). Boldin is just by name.
I think the problem with rating Flacco is we really don't know his full potential in Cam's offense. Any QB in his system is going to be hamstrung. So honestly I cannot say whether he is overrated or underrated. Conversely, any RB in Cam's system is going to be big time highlighted, so naturally overvalued as HoustonRaven correctly says.
I will say certain aspects of individual players games are underrated or overrated. I'd say that Ray Rice as a runner is slightly overrated... lack of breakaway speed, doesnt maximum the gain when little yardage is available, and is not great in short yardage situ-s. Conversely, his contribution in the pass-game is underrated. He is a dynamic weapon that just isn't praised enough.
Flacco's accuracy is underrated. He is extremely accurate. I'd say his grasp of knowing what the defense is doing each play is overrated. He needs to improve this.
Other Overrated/Underrated Aspects of Individuals...
Ray's value in pass coverage.. Way overrated... Honestly should be off the field.
Boldin's ability to separate from DB -- Overrated
LWebb's coverage skills --- Underrated
Ngata's ability to beat doubleteam blocking --- Way underrated
Sam Koch pinning teams inside the 10 --- Underrated (although I will say 2010, he was AMAZING at it... 2011 he wasn't as adept)
Suggs passrushing prowess -- Slightly Overrated -- He is really good but not in the class of a Ware/Freeney/Allen/Cole at that specific skillset. Still think he feasts on weaker OTs and gets his Sacks numbers during those games (+ Pitt games when BigBen holds the ball too long) but does get shutdown by the best OTs in the league. (Look I'm not commenting on Suggs as the complete package b/c I think he is the best DE/Hybrid OLB against the run in the NFL)
How about the whole offensive line?
The media and people outside our fan base (especially the Steeler fans) seem to have a notion that our offensive line is a top ten unit in the league. This was the case from 08 to 09, but since then our offensive line has been poor to average. We have had some overrated players on our line, and it has not helped the development of Joe Flacco or even Ray Rice lately. 2010 we where perhaps one of the worst units in the league, in 2011 we where better but nothing special.
The most overrated Raven is the next guy the Ravens sign off the street. Half the posters here will talk the guy up like he's the next great find and is going to be the key to the offense or defense this year - maybe even a Pro Bowler.
Then the guy will sit the bench or be waived.
There are a few different meanings of "overrated" being thrown around in here.
First, there's the "overrated" that comes with being a superstar on the downslope of your career. You can argue that Matt Birk, Ray Lewis, and Ed Reed all show signs of this. They are not the players they once were, but I hardly think that's worth calling them overrated... "declined" would be a better term. Every one of them is worth their starting position... if not necessarily the superstar status they've retained through their slow descent.
Second, there's the "overrated" that comes with being known to be great, but when there's still a question of just how great. Ray Rice is a phenomenal player. He gets a lot of flak on here for being called elite when it's a measure of his overall game and not of one defining skill. He's a total package... not the fastest runner or the strongest or the smartest or the best receiver or the best blocker but so good at all of those things that he's better as a whole than everyone else (or most everyone else) in the league. He's not overrated unless you insist he's the very best and you wouldn't take an Adrian Peterson or Arian Foster over him under any circumstances.
Third, there's the "overrated" that is most accurate: being generally credited for being better than you are or EVER were. That's Michael Oher. Oher is not a bad player and we're a better team with him on the field... at right tackle, blocking the second-best pass rusher and being a mauler in the running game. He's hyped up as some awesome LT prototype, but he's really not. He certainly shouldn't be receiving Pro Bowl consideration. He's easily the right answer to this question.
Pollard, Ellerbe, and McClain are not well-known enough to be overrated by anyone other than hardcore Raven fan optimists.
Anquan Boldin could be seen as overrated, but he could more accurately be seen as misused, or perhaps just not being allowed to live up to his full potential. More on that in a moment.
Joe Flacco is not overrated. Very much the opposite. First, there's the four consecutive seasons with playoff wins. That doesn't happen by chance and it sure as hell doesn't happen by virtue of your supporting cast alone, or Kyle Boller would still be quarterbacking here after taking us to multiple Super Bowls. Second, there's the fact that he's done that in his first four seasons, during his growing process. We underrate him because he started off so good that we expected him to become a premium QB soon after, and the weight of our expectations is simply too much. He's not the best quarterback in the league, probably not in the top five... but he's good enough to win with our team and to win a Super Bowl. He came within one drop of us being there this past year. We might get there this year... or we might not. Who knows? But we won't go into a tailspin and fall to 6-10 because of him. Not even without Suggs... not unless a lot more people get hurt or begin to suck.
Joe Flacco is underrated because people see the wins, they see his stats, and they assume that it must not have anything to do with him. Most QBs with those stats are mediocre players on mediocre or bad teams. Joe Flacco has those stats because those are the stats he needs to win. Would you rather see him be Matt Stafford, needing 5000 yards to get a team to 10-6? When we have a lead in the second half, we slow things down, grind out the game, go home with the W. We don't put it up in the air for Joe to get another 100 yards to satisfy his critics. Yeah, sometimes this bites us in the ass... but Joe doesn't call the plays and he certainly isn't given the authority for a wholesale strategic change when he feels the game's momentum turning. And he's had a few bad games along the way, not come through in situations where we needed him to author a comeback or just make something, anything happen to avoid squandering a strong defensive outing. But all that doesn't add up to him being overrated.
Joe Flacco can throw for 4500 yards this season if he has to... but that would mean that our defense is letting up 30+ points a game and we're having to outrace every opposing offense. No one here wants to see that. I just know that if Flacco had a Calvin Johnson or an Andre Johnson or a Roddy White like the other QBs in his perceived tier, we wouldn't be having this same conversation. Anquan Boldin was always excellent... as a #2 receiver. Torrey Smith has breakout potential as a DeSean Jackson or Mike Wallace deep threat, but he's not going to be the complete package. If we're ever able to find that guy for Flacco... watch out.