I get it. Rookies are great. Rookies are fun to own in fantasy baseball. All that upside. All that hope. All that promise. If yours pans out, you get to walk a little taller among your league mates because it was you who knew to pick that guy up. And if you were touting him as a prospect for any length of time before he joined the majors, then it’s an ever better “I told you so.”

But people, please. Don’t let your desire to be the big swinging dick in the locker room cause you to blindly hang your hat on any touted rookie who comes down the pike. Too many fantasy baseball owners just go off the lists from either MLB Pipeline or Baseball America and seem to forget that the rankings that come from those two sites aren’t just based on offensive production. In fact, defensive ability is weighted significantly in the player evaluation.

If you’re mining the minors, so to speak, and looking for players to watch for in fantasy, you can start with the lists from BA and Pipeline, but you have to research beyond that. In addition to reading the scouting report, you also need to see how the player profiles as a hitter. What do his minor league totals look like? How many home runs? How many steals? What are his plate discipline and ISO numbers through the different levels? Has there been growth and/or improvement? That’s what fantasy owners care about. How many times have you seen a player thrive in the big leagues but sucked in fantasy? The slickest glove in the world isn’t going to win me any fantasy leagues unless it comes attached to a 40-home run hitter who also hits for average.

But for whatever reason, people still go nuts for every single rookie primed for a call-up. Like how about Mets shortstop Amed Rosario? People are going bonkers over this kid and have been super-antsy about picking him up early so they don’t miss out. Miss out on what? Has anyone here ever looked at Rosario’s numbers? He may be the Mets No. 1 prospect, but it certainly isn’t because of his bat or his legs.

Since joining the Mets organization in 2013, Rosario has shown below-average plate discipline with his low walk rate and a K-rate that hovers near 20-percent. He’s never posted an ISO above .167 and the six home runs he’s hit this year are a career-high for the 21-year old. But before you start talking about raw and developing power, make note that Rosario is currently in the Pacific Coast League (PCL) which is a notoriously hitter-friendly league. And on top of that, his home park in Las Vegas ranks as the fourth-most hitter-friendly park in the PCL according to MiLB.com ballpark factors. So yes, he’s got more home runs right now, but that’s why we look at ISO for a better indication of burgeoning power.

The only legit major league hitters who play regularly and have never had a .200-plus ISO in the minors at some point are the ones who steal 50 bases. But those big league burners were always burners and have the numbers to prove it. Billy Hamilton was swiping 100 bags a year during his time in the minors. Jonathan Villar would swipe 30-40 bags a year down there. Hell, even a guy like Kevin Kiemaier had multiple 20-swipe seasons down on the farm. Rosario? Nineteen thefts last year. That’s his career-high to date. Can’t say that bodes well for game-breaking speed.

Now I don’t want to sit here and dog Rosario. Not at all. I think he has tremendous potential to be an outstanding shortstop for the Mets for years to come. But that doesn’t mean he’s good for fantasy purposes. Remember Rey Ordonez? Great defensive shortstop for the Mets but he would make Francisco Cervelli look like a beast at the plate with the way he swung the bat. He also had a career-best 11 steals one season. He was terrible for fantasy owners but was an integral part of those Mets teams, one of which went to the World Series in 2000.

If you want a more recent example, let’s take a quick look at Braves shortstop, Dansby Swanson. He was a highly-touted prospect coming up through the minors and there’s probably not a day that goes by where the Diamondbacks aren’t wishing they could trade Shelby Miller back for him. But Swanson’s game is his glove, not his bat and you don’t even need to dive too deep into the numbers to see that. He never profiled as having big power or great speed, yet because of his ranking by Baseball America, fantasy owners were drafting him as if they were looking at a potential 15-15 player. Not to put words into other people’s mouths but there’s also a good chance quite a number of people think he could be a 20-20 threat. That’s not happening and his numbers right now can confirm that, even with his recent hot streak.

Again, this isn’t to sit and crap on young players who might be great in real life but bad for fantasy. This is to point out that these types of players exist and just because a prospect is in the Pipeline’s Top 50, doesn’t mean you should draft them. If you want a rookie with great fantasy upside, study those offensive numbers. Those are the ones to target.  Rosario, right now, has more potential of being Alcides Escobar than he does being Carlos Correa.