Srbija, her only titles after RG were MM titles, she reached only one PM final and few other significant SFs (3 to be precise). So, if you believe that she will tank all events apart from slams and PMs for the rest of her career, I need to ask you if believe that she'll ever win a title again.
1. I'm not talking here about Ana's performances in last 5 years, but just about last 20 months when this fitness/body issue become so obvious. Also, in this my recent predictions I'm not saying anything about Ana upcoming results till end of hers career or something like that, but just about next month February if we talking about day-to-day events.
2. You forget that MM-YEC is not classic MM tournaments. So playing just 3 matches overall to reach MM-YEC title where also is included day pause, at seasons ending tournament, is actually argument in my favor! And that MM Linz title coming from season where she worked with Heinz and don't have such fitness problems (for example, hers results at P5 events in 2010 are better than at PM, not way worse like in 2011-2012).
3. "Tank" is not best term to describe this phenom with Ana. Do You really think that Ana played well on Hopman Cup round robin, and than suddenly decide to tank FINAL!? She simple underperform thanks to fitness problems when it come to play day-to-day since 2nd half of 2011, and in other day-to-day cases add fact that she knows that her body will underperform anyway so to prevent injuries she also much more using hers back-up game (and in Ana case plan-A>>>plan-BS). That's why Ana playing already about 20 months in the row on TOP10 level at tournaments with day pause between matches, and barely on TOP100 level at events with day-to-day schedule!
4. If she not improve hers fitness and be able to recover body on daily basis - hers best shots are Indian Wells and Roland Garros, two-weekers where she is multiple finalist and former champion. With this state of fitness and body here is scenario for hers MM title: R1-bye, R2-win, QF-win by w/o, and will be very helpful if during SF or final there will be big rain-delay pauses, but if she must to win 4 matches in 5 days (normal MM/P600 schedule) - I don't see it coming any soon.