Here's how I sum Joe Flacco up. He isn't an elite QB and I don't think there is much debate about that anymore or at least there shouldn't be. Again these are based on my own opinion and not how you may see them and you can form your own opinions and list.
To me there are truly only 3 elite QBs playing today. Brady, Brees and Rodgers. The next level has several more like Big Ben, Matt Ryan, Carr, Wilson, Prescott, Manning (yes Eli is in the 2nd tier), Cousins and Newton. I have deliberately excluded the 2nd year QBs Wentz and Goff and if I were to include them, they would also reside in this category. Deshaun Watson perhaps belongs in this category as well but not enough data to categorize him right now. After these QBs come the third tier of QBs that include Flacco, Dalton, Tyrod, Case Keenum, Nick Foles ( he actually threw 7 TDs and a perfect passer rating in a game and has also led the Eagles to a SB start this year and perhaps could qualify to be bumped into the bottom of tier 2), Bortles, etc.
I may be missing a few QBs but I think I may have covered most of them. To me the closest QB comparison to Flacco is arguably Nick Foles. They both have similarities in that they can go on a run that makes them look great. Foles has made a pro bowl as well unlike Flacco. He has also thrown 19 td passes to 0 interceptions in 2013 eclipsing Flacco's 2012 11TDs - 0 ints except Flacco run was where it mattered the playoffs culminating in a SB. So let's not scoff at this comparison because I think it is very appropriate.
This post will invite a lot of homer criticism but this is how I feel right now and feel very comfortable with it.
ps: I forgot about Luck. I think he hovers between tier 2 and 3 and right now he would top the list of tier 3 QBs based on his injury history and production lately.