10 Fantasy Baseball Players to Buy and Sell for Week 15

Alex Wood has been one of the biggest surprises in the first half this season. Should you sell high on the budding ace, or hold tight?

We made it! After 15 weeks of grinding it out, we get a week to relax and enjoy the All-Star Break. The sane thing to do would be to sit back, crack open a cold one and watch some dudes absolutely obliterate baseballs.

However, if you prefer fantasy championships to your sanity, this is the perfect time to evaluate your team.

Maybe your team has been plagued by injuries and it is time to cut bait on guys you would have preferred to hold on to because you're in win-now mode. Maybe you have a comfortable lead in the standings and can afford to take a chance on some buy-low players in hopes of a bounce back heading into the later stages of the season.

Regardless of where your team sits right now, you should always be looking to take advantage of market inefficiencies on players.

Perhaps a slow start is just a product of bad luck and a small sample size. Maybe the reason you're in first place is due to the stellar but possibly unsustainable play of some players you can sell high on. If you're not sure whether you should hold or fold on a player, don't sweat it. That's why we're here.

The following 10 players have seen a perceived change in their fantasy stock, and we'll attempt to decipher which warrant taking action.

Buy Luis Severino

Luis Severino has been flat out dominant for most of the season, but many were leery to buy in on him being an elite fantasy option after the volatility he showed last season. So, after watching him post a 5.46 ERA over his final five starts heading into the All Star Break, some owners may be wondering if his strong start to the season was a mirage.

I'm here to tell you that it was not. Even during that rough five-start stretch, Severino still posted a 3.13 xFIP. The only real issue during that stretch was his opponents' .366 BABIP, up from the .267 BABIP they posted against him in his first 12 starts.

Severino still has the fifth-best xFIP (3.05) among qualified starting pitchers on the year, as well as the eighth-highes strikeouts-per-nine-innings (K/9) at 10.46. If you can find a Severino owner who is ready to push the panic button due to his recent cold streak, take advantage because the numbers indicate his impressive first half should carry over.

Add Trevor Cahill

Trevor Cahill has been eased back into action in his first two starts off the disabled list, but he has looked like every bit the dominant pitcher he was prior to the injury. If he had enough innings to qualify, Cahill would rank ninth in xFIP (3.16) and fifth with a dominant 11.19 punchouts per nine innings.

While it is hard to believe after a career of mediocrity, Cahill has become an elite swing-and-miss pitcher this season. If qualified, his 68.3% contact rate against would tie Robbie Ray for second among starting pitchers, while his 13.5% swinging-strike-rate would rank seventh.

Even if you don't believe in Cahill's dominance this season (he has only pitched 50.2 innings), it isn't like you have to invest much into him. He is still available in nearly 70% of ESPN leagues, so more likely than not, you can just pick him up off your waiver wire.

Sell Eric Hosmer

After posting the American League's best record in June, isn't it beginning to feel like the Kansas City Royals have that magic again? Well, Eric Hosmer has been feeling the magic all year. His bloated .352 BABIP has helped him post what would be a career-best .318 batting average, while an equally lucky 20.3% home-run-to-fly-ball-rate has helped him launch 12 long balls, in spite of a 30.5% hard-hit rate and 21.2% fly-ball rate that do not profile as anything near a power hitter.

Another good indicator of luck is examining expected wOBA (xwOBA) compared to actual wOBA. Hosmer's xwOBA of .353 is 16 points below his actual mark of .369 and is just another indicator that some regression is headed his way.

Here's perhaps the most damning thing about Hosmer's fantasy prospects -- even with his lucky first half, he still ranked just 15th among first base eligible players in standard scoring. With negative regression likely headed his way, and him being only a fringe-start worthy player to begin with, it is fair to wonder how much Hosmer is really going to be worth in the second half.

Hold Alex Wood

This one might seem strange, because traditionally, when thinking of a player to hold, it is because they have been underperforming and shouldn't be sold low. Alex Wood, on the other hand, has been unbelievable in the first half, posting a perfect 10-0 record and pristine 1.67 ERA. So, why hold? Because the natural train of thought in fantasy when you have a player performing far better than they ever have in their career is to sell high on them.

The fact that we've never seen Wood's dominant form before doesn't mean it isn't legit. While he probably will lose a game at some point and it would be surprising to see his ERA below 2.00 at the end of the year, Wood's peripherals point towards one of the league's best pitchers, rather than one of the luckiest as some might suggest.

If qualified, Wood's xFIP (2.57) would lead all starting pitchers, as the current leader is Corey Kluber (2.65). He's also posted an insane 63.5% ground-ball-rate, which is just barely enough to edge out Lance McCullers (63.0%) for the league lead. He is the only pitcher with a ground-ball rate above 50.0% that also has a strikeout rate above 30.0%, as his 30.9% rate ranks sixth. That lethal combination explains exactly why Wood has been so untouchable thus far.

He's likely to come down to earth some, but his numbers thus far are certainly not a mirage. Don't sell high, just enjoy the ride.

Buy Matt Carpenter

Matt Carpenter has absolutely destroyed baseballs this season, posting the league's eighth-best hard-hit rate (45.1%), which is easily the highest among second base eligible players. Over the past 30 days, he has a hard-hit rate (48.8%) that trails only five players.

Among players in the top-10 in hard-hit rate, Carpenter's .256 BABIP is by far the lowest, with the next-lowest being Cody Bellinger's .282. In fact, Carpenter ranks inside the bottom-20 in BABIP this season, a clear indicator of bad luck.

He's also posted a much higher xwOBA than wOBA, trailing only Miguel Cabrera in terms of the difference there. His xwOBA (.406) actually is the 12th-highest mark in the league and is, again, the highest mark among second base eligible players.

With some better luck on balls in play, Carpenter's lackluster .237 batting average and .356 wOBA both should rise significantly, while his excellent hard-hit rate and fly-ball rate should continue to allow him to be a strong contributor in the power department.

Sell Julio Teheran

Julio Teheran is a pitcher that has shown an ability to put up usable fantasy numbers in the past, so after allowing just two runs in his past two starts, some might be inclined to take a flier on him heading into the second half.

Let them.

Even over his past six starts, in which he has a respectable 3.68 ERA, Teheran has an ugly 4.72 xFIP. On the year, his 5.25 xFIP trails just five starting pitchers for the league's worst mark. He's also contributed little-to-nothing in the strikeout department, with a 6.53 K/9 on the year and a 5.89 K/9 over his recent "hot" streak.

Teheran hasn't posted an xFIP below 4.00 since 2014, and everything indicates that his downward spiral is continuing this season. If you can sell him for anything above a replacement-level player, do so now, because his peripherals suggest he belongs on the waiver wire.

Hold Rougned Odor

Rougned Odor has been featured in this article a few times this season due to his extraordinarily bad luck on balls put in play, which as made him a terrific buy-low option. With some positive regression hitting him in recent weeks, many owners will be trying to take one last stab at a buy-low offer.

If you have held onto him through all of his struggles, don't give in now, because he still has more positive regression headed his way. Even with some better luck in recent weeks, Odor's .244 BABIP still ranks 10th-worst among qualified hitters. Among players with a BABIP below .250, only Manny Machado and Joey Gallo have a higher hard-hit rate than Odor's 37.8% mark. Over the past 30 days, Odor has upped that hard-hit rate to 44.7%, which ranks 14th among qualified hitters during that time.

His 75.8% contact rate is problematic for his batting average, but with some better luck on balls put in play, it should rise to somewhere closer to his career .256 mark. The power has been there for him, with 17 long balls already, and his hard-hit rate suggests that he may be able to approach last season's career-best 33 home runs with a strong second half.

Sell Eric Thames

Eric Thames was a prime sell-high candidate early in the year due to an inflated BABIP and a limited career track record. At this point, neither is much of a concern. His BABIP has normalized, and his .272 mark could even see some improvement over the second half. His 23 home runs are also no joke, and his 42.5% hard-hit-rate and 43.9% fly-ball-rate suggest more strong contributions could be coming in the power department moving forward.

So, why the concern? Well, thanks to a .208 batting average and 35.8% strikeout rate against lefties this season, Thames appeared to be put into a platoon of sorts over the last couple weeks. Thames took a seat in five of his final 11 games, a very troubling sign for someone who was previously considered a set-and-forget option at first base for fantasy owners.

If you can get an owner in your league to buy high on Thames based on his 23 long balls, it might be time to part ways with the powerful breakout player.

Buy Jeff Samardzija

Jeff Samardzija has become a staple in this article, thanks to consistently having one of the biggest differences between his ERA (4.58) and xFIP (3.09). Among qualified starting pitchers, only six have a stronger xFIP than Samardizja's, while none have a better strikeout-to-walk-ratio (9.07).

After a slow start, Samardzija has been much more effective recently, allowing three or fewer runs in all but two of his past 11 starts. He has a 4.02 ERA during that time and has a ludicrous 72-to-4 strikeout-to-walk rate in 71.2 innings.

While Samardzija's league-leading walk rate is impressive, it might be his downfall, too -- he is simply catching too much of the plate. His season numbers likely never will come to represent his peripherals, but there's no denying that his .323 BABIP against and 67.1% strand-rate should see positive regression over the remainder of the year.

Add/Buy Michael Wacha

After a disastrous midseason slump, Michael Wacha has really turned things around in his past four starts, posting a 2.08 ERA and perhaps even more impressive 2.81 xFIP. On the year, his xFIP is down to 3.84, which suggests there's plenty of room for improvement on his 4.10 ERA.

He's also been striking batters out at a higher clip this season, posting what would be a career-best 9.05 K/9 on the year and a 10.80 K/9 over his past four starts.

What is really impressive about his recent success is that he has been able to post a 2.08 ERA in spite of a .393 BABIP against during that time. This is a trend that has plagued Wacha all season long -- his .347 BABIP against would rank as the third-worst mark in the league if eligible.

Wacha is still available in over 50% of ESPN leagues, so there's a chance you can still pick him up off your waiver wire for free. If he's owned in your league, see if his owner is willing to sell low based on his pedestrian season-long numbers.