IF Rafa is going to come back to anywhere near his best there will be obvious signs.
First, you will see him looking more fit. More muscle, less winded, reaching balls with enough time, and the forehand doing consistent damage, winning at least 70% of deciders.
Second, you will see better results on clay.
Signposts to look for:
Semi in Monte Carlo
Final or Win in Barcelona
Madrid irrelevant but at least 3-4 wins needed...
Rome final or win
Bottom line, he needs about 18-20 clay match wins before the RG quarters.
If he can do that, I give him a good chance to win RG.
But if he keeps getting beaten in SF by ordinary mortals or earlier on clay, forget it. Frankly, I don't see it happening this year. He has a lot of work to do if he is going to do it.
Just to put this into perspective, remember his record on clay, or you can go and check it...
Between Jan 2005 and Dec 2013 (9 full years) Rafa lost only 4 matches prior to FINALS on red clay (exc. Madrid's 2012 blue clay loss to Verdasco):
2012: Madrid [Blue Clay] - Verdasco in R16
2009: Roland Garros - Soderling in R16
2008: Rome - Ferrero in R32
2005: Valencia - Andreev in QF
2005: Buenos Aires - Gaudio in QF
In Finals in that time period, he lost 3 times to Novak in the Madrid, Rome, and Monte Carlo Masters, twice to Federer in Madrid and Hamburg Masters, and once to Zeballos in Chile in his 1st tournament after 7+ months out.
That's a 267-11 record (including the blue clay loss). That's an unbelievable 96% winning percentage and a 98% finals percentage.
At one point, he won a record 81 straight matches on clay, in over 2 years, between Andreev in Valencia, before being beaten by Federer in Hamburg..
This is almost as pure a surface domination and demolition as one is going to get in this sport.
However, since then, it's like the mud-gate opened.
Rafa lost on clay at 2014 Monte Carlo to Ferrer in the QF
Rafa lost on clay at 2014 Barcelona to Almagro in the QF.
Rafa lost on clay at 2014 Rome to Djokovic in the Final.
Rafa lost on clay at 2015 Rio to Fognini in the SF.
Rafa lost on clay at 2015 Monte Carlo in the SF to Djokovic.
Rafa lost on clay at 2015 Barcelona, again to Fognini, in the R16.
Rafa lost on clay at 2015 Madrid to Murray in the Final.
Rafa lost on clay at 2015 Rome to Wawrinka in the QF.
Rafa lost on clay at 2015 Roland Garros to Djokovic in the QF.
Rafa lost on clay at 2016 Buenos Aires to Thiem in the SF.
Rafa lost on clay at 2016 Rio to Cuevas in the SF.
That's 9 losses on clay prior to the Final in a little more than 2 seasons, about double the amount in the previous 9 years combined.
There is a bit of good news. During this period he did win 5 clay titles with 2014 Roland Garros his 9th there, and his14th and last major title:
2014: Rio [ATP 500] (Dolgopolov), Madrid [Masters 1000] (Nishikori ret.), and Roland Garros [Major] (Djokovic).
2015: Buenos Aires [ATP 250] (Monaco), Hamburg [ATP 500] (Fognini).
On other surfaces he has faced serious troubles, on grass, on hard courts. For most other players, 5 titles on clay in two + years would be fine.
But on clay, for him, the King of Clay, it's a decline of tragic proportions, one that will take a heroic, nay, a herculean effort to overcome. It's not unexpected. It has happened to the best of them.
That said, I still hold out small hope that he can do it if he really wants it. He is too formidable and great a player on clay to write him off completely.
But one has to worry that he will again be tempted by practicing and playing too much on hard courts, where the stamina and patience are generally less needed, but more jarring and risk of injury is higher for him.
Respectfully,
masterclass