There are good seasons of Survivor, and there are seasons that just never get off the ground. Survivor: San Juan Del Sur looked like it would be the latter, until a run of solid episodes near the end redeemed it.

After the first Blood Vs. Water was a critical and ratings success in 2013, the show returned to the same format this season – only to find that lightning hadn’t struck twice.

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Even Jeff Probst, Survivor‘s biggest cheerleader, acknowledges the struggle of San Juan Del Sur. “We came off of four fantastic seasons in a row: Philippines, Caramoan, the first Blood vs. Water and Cagayan, he says. “So this one just feels different, because it follows such great seasons. But it got a lot better as it went along.”

But even middling seasons of Survivor can be fascinating, and the long-running CBS series remains the gold standard for competition reality shows. Here, Probst, 53, tells PEOPLE what went wrong with this season – and what went right.

This season started off slow. Why?

We cast a lot of people who didn’t know how to play. They were learning their game as they went along, which meant that it started out pretty slowly. I don’t know that I’m a big fan of casting so many people who haven’t watched the game, but I did enjoy watching how frustrating it was for the good players.

How so?

If you base your Survivor approach on game theory, then you make your best move on the assumption that every other player is making their best move. But the people who didn’t know the game were unpredictable. The clueless players became a new obstacle. So some people got really frustrated. There’s no getting into Keith’s head, because he didn’t even know what an alliance was when he started playing this game. You can’t guess what he’s going to do.

Was there anyone on the cast that you didn’t want?

Jon and Jaclyn. I thought they were going to be boring, and wouldn’t offer anything to the season. But [CBS President] Les Moonves wanted them, and he was right.

You cast John Rocker, who trash talked his way out of the game on Day 8. And then, his girlfriend Julie quit the show! Do you regret casting them?

Everyone brings their own baggage into a season, and John Rocker had a lot of it. That’s fascinating TV. Looking back, he wasn’t that villainous on the season. He was paying for his sins from years ago. We wanted him on another season, but it didn’t work out. So we put him on this season and he brought Julie along. Her behavior speaks for itself. We have Missy playing the game on an ankle that could very well be broken, and Julie quit because she was hoarding trail mix? Yeah. Bad choice.

You seemed to not like a lot of these people. Were you on edge all season long?

It’s not about not liking them. It was that a few things just didn’t work out like we had hoped. There was an alliance who was discussing how to split rewards evenly, how to make sure that it was fair for everyone. And that’s not what Survivor is all about. So there was a lot of frustration this season; I’m always worried when things are gelling like I’d like them to, but that’s Survivor for you!

So we’re down to five contestants left. Break them down for me. Let’s start with Natalie.

Natalie and Nadiya were question marks for me, whether to cast them. I’m always wanting to put likable people on the show, and they weren’t likable on The Amazing Race. As it turned out, their stories couldn’t have been more different, which surprised me. The best thing that happened to Natalie was that Nadiya was voted out first. We’re watching a woman play with nothing to lose. She’s playing for revenge. She’ll make big moves. That’s a lesson for future players: You need to be able to play as if there’s not a million dollars at the end. Swing for the fences. If you make it to the end, you have a resume to plead to the jury. At this point, on the island, Natalie had momentum, you could feel it. And there was an energy surrounding Keith.

Keith?!? Seriously?

It’s amazing. On Day 1, he had no idea how to play this game. Now here we are in the finals and he’s a favorite to win. He’s got a great story. ‘Look at me! I’m a guy who didn’t know what I was doing. I came out so my son could have this experience, but I’m wiser than I look. I figured it out, and you never voted me out.’ If he says it right, he could win the game.

And then there’s the mother/daughter duo of Missy and Baylor.

They played two very different games. If I were Baylor and made it to the end, I’d say, ‘I’m just a young kid, but I played this game well. You may have some more life experience than me, but I did very well for a 20-year-old girl, and that should be rewarded.’ Missy has a different argument. She should say, ‘I got this far with my limited skills. When I hurt my ankle, I transitioned my game and stayed in the competition.’ I’m not sure that either of those arguments will sway a jury, but those are their best arguments to make.

What about Jaclyn?

I may be alone in this, but I think Jaclyn can make a case to win this game. She’s a dark horse, but she’s ahead of Missy and Baylor. If she can make it to the end by winning immunity, she has a shot. She needs to say ‘I was with my boyfriend, but I was playing this game hard; you just didn’t see it.’ It’s an outside chance, but she’s got it.

So tease us about next season.

Survivor keeps surprising me. I’ve taped 30 seasons now and I never know what to expect. And season 30, which I’ll announce at the finale, delivers. That unpredictability is why I love Survivor so much.