I have some issues with Rafa's game at the moment that really don't have much to do with him allowing Tsonga back in the second set. I think that was actually not THAT shocking (which is not to say it wasn't surprising) considering how bad Tsonga was playing before that, so the sudden improvement in his level was always going to catch Nadal off guard. In many ways, your opponent playing so badly lulls you into a false sense of security, and you struggle to really wake up immediately. It was always going to take Rafa a few games to readjust to Tsonga actually playing like a top 10 player (and when Jo is on, he's REALLY ON). He finally tightened up the screws in the tie-break though, at just the right time.
In any case, as far as what's missing from his game, the obvious thing that really stands out is the serve. At the moment, it's looking the weakest I've seen since maybe 2006. And I'm not even exaggerating. At times you can't even tell if it's a first or second serve. The percentage is obviously high, but the amount of cheap points is staggeringly low. He's not even able to take his opponents off the court to set up a subsequent forehand. It wasn't until late in the match that he mixed things up with some timely aces. But on the whole, he was literally just spinning it in on both sides. It's odd because towards the latter stages of IW, it was looking quite good. If Novak is his opponent tomorrow, Rafa has no other choice but to raise his serving, otherwise holding serve alone is going to be a struggle.
The other thing is his current inability at changing direction with the forehand when he's actually camped on his forehand side. Obviously, Rafa's forehand is always more effective when he's either positioned in the middle of the court, or on his backhand side (after running around it), where he has far more options and the thread of the inside out forehand changes the dynamic of the rally. Nevertheless, the DTL forehand used to be there. Well, not in this tournament. There was one point in particular where Tsonga camped on his backhand side, ran around it, and fire 3 or 4 inside out forehands in the row, leaving the court completely open, virtually daring Nadal to try and go down the line into the open court. When Rafa did, he shanked the forehand long and got broken. That about sums it up.
With that said, his backhand is still looking pretty damn solid, and that is terrific news. We know Nadal's forehand will fire when he really picks up his level. It always does. We know he still has a few gears in him, especially on clay. So the fact that he's hitting his weakest shot well is actually more important at this point.
Anyway, none of this is particularly alarming, as we know he'll improve as the clay season progresses, but if it's Novak in the final, he needs to kick it up a notch quicker than anticipated.