I'm reminded of last year, when at this point Rafa was 13-5 with no titles and having lost in the 1R of the AO to Verdasco, and losing in the SFs of the early clay ATP 250s to Thiem and Cuevas. He had a good run at IW, beating Verdasco, Zverev, and Nishikori to lose to peak Novak in the SF. He retired vs. Dzumhur in Miami, then came back to win Monte Carlo and Barcelona, but then lost to Andy and Novak in Madrid and Rome, respectively, and then of course pulled out of Roland Garros because of injury.
Right now Rafa is 14-4, so one win better than last year. Now of course things were different his year - he had a great run at the AO, and thus started the year much better than last year. But since then he's looked more similar to 2016 in terms of results.
If I remember correctly, there was a sense he was "kind of back" in clay season last year after Monte Carlo. It was his first big title in almost two years going back to 2014 Roland Garros. His Rome/Madrid results were a bit disappointing, but understandable considering who he was facing. He entered RG not as the favorite given Novak's level, but as a serious contender.
I don't think we can overstate how important clay season is for him this year. He really, really needs to win at least one clay Masters to get back in the saddle. Barcelona would be nice, but he really needs a Masters title, and I think also he needs to beat one of Roger, Novak, or Andy. Consider his current streaks against those three:
Roger: 0-3 (going back to Basel of 2015)
Andy: 0-1 (Monte Carlo 2016)
Novak: 0-7 (going back to Monte Carlo 2015)
That's clearly a concern. Actually, playing Novak now might be just what the doctor ordered.