Which side of the draw has collapsed more?
In terms of seeded players going out?
In the top half we've lost Kvitova, Ivanovic, CSN and Cibulkova.
Remaining top seeds are Serena, Bouchard, Pennetta, Azarenka plus there is also Katya Makarova who normally elevates her game at slams (and is so near to being a top 16 seed)
In the bottom half we've lost Halep, Radwanska, Kerber and Venus (who while not top 16 was considered a major threat given her recent performances)
Remaining contenders are Sharapova, Jankovic, Wozniacki, Errani, Safarova. (Plus Bencic is obviously going to be strong in the future and is demonstrating some serious poise now; Peng also playing some excellent stuff)
Personally I actually think the draw remains fairly balanced. Serena is a bigger threat than Maria which makes life tougher for those on the top half of the draw, but I'd say broadly speaking you have 3 likely contenders from both sides: Serena, Bouchard and Azarenka for the top half; Maria, JJ and Caro for the bottom half. Plus you still have a few spoilers on both sides who are capable of making the SFs and maybe the finals if things go their way. If iI were to differentiate between the two halves I'd say the bottom half has more strength in depth (it's lower ranked players are more likely to cause an upset IMO) but the top half has slightly better slam credentials.
Whilst there have been a lot of upsets this slam, I'd say it's not yet on a par with Wimbledon 2013, and is probably still ahead of RG 2014 (although if one of Maria or Serena lose in R4 it probably heads that way)
All of the 6 players I picked as likely contenders still have serious flaws in their credentials for this slam given 2014 form so I think it's actually going to be fairly interesting how it pans out.
Maria SharapovaAgenlique Kerber - Victoria Azarenka - Nastya Pavyuchenkova
Yanina Wickmayer - Laura Robson - Johanna Konta - KiKi Mladenovic - Sabine LisickiAna Konjuh - Aga Radwanska - Julia Goerges - Kimiko Date Krumm - Lucie Safarova -