The end of June signals the approximate halfway point in the season.

Which for me means no more hiding behind the sample-size scapegoat. It's time to make some tough calls.

I don't relish the opportunity. I've worn the baseball-analyst hat for long enough to know how abruptly a player can reverse his fortunes. Writing off a Fantasy mainstay before his ownership has completely tanked is just asking for trouble, as players like Andrew McCutchen, Masahiro Tanaka and Jose Quintana have demonstrated over the past few weeks.

Analytics has done so much to improve our understanding of the game, to the point we can explain what a player has done, should do and (presumably) will do with some measure of confidence, but that's only assuming he does nothing to alter his profile. 

Struggling players are the ones most likely to tinker. One small mechanical change, speaking for both hitters and pitchers, can completely transform a player. Most of the time we have no forewarning of it, and sometimes we don't even hear about it after the fact. It's why, for all the data available to us today and the army of number crunchers eager to break it down for us, we should never be too sure about a player.

But at some point, we have to move on, right? We can be paralyzed by fear and never make a trade, never grab the hot hand off the waiver wire, never move from our intended path at the start of the season, but we're probably not going to win that way.

And frankly, player value is constantly evolving. If you read it any other way, you're reading it wrong. No bit if analysis comes without an expiration date. It's always intended for "now and for the foreseeable future, " which for the purposes of this column means the rest of the season.

You'll notice I'm not ready to pound the gavel for every high draft pick who has let us down this year, and even for these 12, I'm not suggesting they're worthless or even droppable. But we shouldn't expect their fortunes to change much going forward.

Enough is enough!
Jake Arrieta Chi. Cubs SP
For a while, I held on to the idea of his strikeout rate being too high for him to fail, but in five starts this month, Jake Arrieta has just 7.6 strikeouts per nine innings. The bottom line is he isn't throwing as hard, dropping a couple miles per hour from just last year, and his struggles date back even to those harder-throwing times. Over his past 33 starts, he has a 4.48 ERA and 1.28 WHIP. He's still startable in his current form, but I'm ready to admit he's not the ace you're looking for.
Ian Desmond Colorado LF
Turns out Coors Field wasn't enough to continue Ian Desmond's BABIP-breaking ways of a year ago, but it's hard to analyze a player effectively when he up and changes his profile on us. His ground-ball rate is now an astonishing 62.8 percent, which would tie for the major-league lead if he had the at-bats to qualify, and his soft-contact rate would be in the top five. It explains how he has just five home runs in 214 at-bats while playing half his games at a hitter's haven, but it doesn't offer much hope for a turnaround, especially since his plate discipline is also horrid.
I just don't even care anymore. More than once during his time in the majors, Carlos Gonzalez has slumped for an entire half-season. We'd write him off. He'd come back with a vengeance. We'd wallow in our miseries, weeping for those who sought out our miserable advice. But now he's hurt, contending with a shoulder injury that may or may not sideline him for several weeks. And frankly, my outfield needs aren't great enough for me to wait around and hope. I'd give up some expendable for him in a five-outfielder league, but I don't know that I'd want to devote even a bench spot to him in something shallower.
Adam Jones Baltimore CF
Funny thing is Adam Jones' numbers would still measure up in the offensive environment where he emerged as a top-flight Fantasy outfielder 3-4 years ago, but by today's standards, they're just so ordinary. Everybody who's anybody hits 20-plus homers nowadays, and while he might come closer to 25, it's really all he brings to the table. He doesn't hit for much power otherwise and doesn't get on base a lick, limiting his RBI and run potential. He hasn't done anything especially out of character to this point, and yet he has been outscored by Keon Broxton and Jarrod Dyson.
Jonathan Lucroy is still my fourth-ranked catcher, but there are only three catchers I hold in any regard: Buster Posey, Gary Sanchez and Salvador Perez. He still has the best chance of anyone outside of that three of joining them given all the times he has done it in the past, but I think we're too far into this Robinson Chirinos power binge for Lucroy to make any headway in the playing-time department. He basically gets a 60 percent share, and while he's still making contact at a high rate, it's unusually weak contact with a high ground-ball rate. I'm not sure he can get hot enough with that profile to disrupt the status quo.
Seung-Hwan Oh St. Louis RP
Seung-Hwan Oh has had better eight-game stretches this year than this current one in which he has allowed seven earned runs to raise his ERA from 2.57 to 3.57, but the low point for his WHIP is 1.30, which clearly isn't closer material. Among closers with a WHIP below 1.00 last year, he trailed only Aroldis Chapman and Kenley Jansen in strikeouts per nine innings, but his slider just hasn't been as effective this time around. The only reason the Cardinals haven't pulled the plug on him yet is because they have nobody better, but if you play in the one-third of CBS Sports leagues where Felipe Rivero or Justin Wilson is available, you do. 
Gregory Polanco Pittsburgh RF
The sales pitch for Gregory Polanco coming into 2017? "Genuine upside at a position of need!" Yeah, that's out the window now with outfield undergoing a complete transformation, introducing Aaron Judge, Corey Dickerson, Scott Schebler and so many more to the Fantasy spotlight. The 25-year-old is striking out less than ever, but it's such weak contact that the Pirates aren't even committed to playing him every day anymore. And even if he gets back to the form he showed last year, he wouldn't be a surefire starter in mixed leagues.
The good news is Rick Porcello has a .367 BABIP, second-highest among qualifying pitchers, and from that metric alone, you can infer he has better times ahead. But how much better? See, the bad news is that he has allowed the hardest contact of any qualifying pitcher, according to FanGraphs, and also ranks in the top 20 in line-drive rate and fly-ball rate. It's a profile that should yield a high BABIP as well as a high home run rate, so at this point, bringing that ERA below 4.00 is a pipe dream. He's still usable in this environment but hardly a must-start and far from ace-caliber. 
I mean, it's Hanley Ramirez. How many times does he have to let us down in his career before we stop falling for it? Sure, he had a redemptive season for the Red Sox last year, kind of like that one he had for the Dodgers in 2013, but his shoulder injury this spring should have tipped us off to another year of frustration. I could understand paying the price tag at the time given that first base was somehow lacking in standouts, but with all the breakouts at the position this year -- from Eric Thames to Cody Bellinger to Justin Smoak to Logan Morrison to Justin Bour to Mark Reynolds to Yonder Alonso and on and on -- you should have moved on long ago. 
Tanner Roark Washington SP
This season is the second time Tanner Roark has faked us out. We cried over his banishment to the bullpen in 2015 after an out-of-nowhere breakthrough the year before only to see him stink it up in the role, and then we were amazed all over again when he returned to form last year. But his pitch-to-contact profile is an especially dangerous one in this environment, and while he has managed to limit his fly balls at a time when everyone is looking to hit them, he hasn't commanded his pitches well enough to get away with all the contact. The upside isn't impressive enough for you to suffer through this misery.
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Julio Teheran Atlanta SP
Even when the Braves played at Turner Field, Julio Teheran struggled to keep the ball in the park and looked like he was getting away with something when you compared his ERA to his FIP, so it's not terribly shocking that a move to a smaller venue has turned his numbers upside-down. His 7.58 ERA in nine home starts is probably overkill, but he has compounded the problem by missing fewer bats than ever, striking out three or fewer in four straight starts. Teheran will still have his moments, especially in certain road starts, but this new version in this new ballpark is no standout.
I've gotten a lot of questions about Troy Tulowitzki recently, which I guess sums up the state of the shortstop position. I figured we had stopped counting on him to be a regular contributor to our Fantasy teams last year and all agreed that his current production was simply continued evidence of his decline, but apparently not. I suppose at 32, he's not beyond hope and has even improved his contact rate by a healthy margin, but it's mostly weak contact with a low line-drive rate. At this point, I'd rather cross my fingers with a Franklin Barreto type.

Think I forgot someone? Well, maybe I did, but not if it's one of these struggling studs who I still more or less believe in: Manny Machado, Miguel Cabrera, Rougned Odor, Johnny Cueto, Justin Verlander, Carlos Santana and Matt Carpenter.