Each week, FantasyPros publishes a fantasy baseball trade chart. The chart contains player values designed to help you assess the overall weight of both sides of a trade.

The weekly trade charts also keep track of the changes in a player’s value from the previous week. But sometimes, the reasons for a change aren’t obvious. “Why is player X gaining three points in value this week when player Y, who had an even better week, remained the same?”

Good question, reader. There are many answers as to why any given player moves in value from one week to the next. And in this article, we’ll examine some of the biggest risers and fallers each week, and explain the movement.

Here are some of the most notable risers and fallers in the FantasyPros Week 10 Trade Value Chart:

Risers

Sandy Alcantara (SP – MIA). Week 10 Value: 29. Previous Value: 25. Change: +4

I’ve been slow to move Alcantara up significantly because nothing looked too different under the hood. His 23.4% strikeout rate and 7.7% walk rate are in line with what he’s shown the previous two seasons. His velocity hasn’t changed. His spin rate is actually down on all of his pitches.

The reason for Alcantara’s success this year is that he is allowing much less hard contact than usual. His 86 MPH average exit velocity ranks in the 90th percentile of MLB and his hard hit rate is in the 74th percentile. Even with his stellar season last year, those numbers were in the 76th and 42nd percentile, respectively.

But there’s a lot of data to suggest that pitchers have little control over the quality of contact they allow, at least in terms of how it fluctuates from one year to the next. So, I’ve been slow to come around on the veteran as a top-10 arm.

But we’re past the point of dismissing Alcantara’s ridiculous performance as small-sample noise. His 1.68 ERA and 0.96 WHIP will regress. But after 205 2/3 innings last year, he’s already up to 91 1/3 this season in just 13 starts, which leads the league by plenty. He’s thrown at least seven innings in each of his last seven outings.

Alcantara is not only good, but his ratios take on extra value because of his innings, and he makes up for his mediocre strikeout rate by giving himself the opportunity to pile on more of them. Again, regression in some form is coming. But he should be valued as a truly elite starter.

Fallers

Whit Merrifield (2B – KC). Week 10 Value: 24. Previous Value: 28. Change: -4

I usually give Merrifield a lengthy leash because of his stolen base potential. He’s not the fastest player in the game but his sprint speed has ranked and continues to rank in the top 15% of baseball and he’s an outstanding baserunner. So even at his advancing age, he’s capable of swiping double-digit bags in any given month.

But that stolen base upside usually comes with some batting average, and this year, Merrifield is batting .227 with a .268 OBP entering Tuesday’s action. And when you have just seven steals and haven’t attempted a steal since May 24th, well, things like that are going to matter.

Merrifield has a .277 xBA and, again, still has excellent speed. So, despite his incredibly slow season thus far, there’s no reason to drop him like a stone in value. But, he should move down, at least a bit, in case this is the end of the road.

Corey Seager (SS -TEX). Week 10 Value: 18. Previous Value: 22. Change: -4

To be honest, I just don’t think I realized what a mediocre season Seager had been having until I dug into him this week. After all, his 12 home runs lead the shortstop position.

But his 28 runs and 28 RBI are mediocre, at best. Seager has little speed so can make up for any ills with his batting average, but he’s hitting just .223 currently with a .286 OBP. Like Merrifield, his xBA (.291) suggests that he’s been the victim of bad luck. But he’s also hitting fly balls at a career high 41.1% rate, which not only helps to explain the low average but may be a result of him trying to justify his large contract.

Seager still has plenty of value, but his poor surrounding cast is going to limit his counting stats, which in turn needs to limit his trade value.

Cody Bellinger (OF – LAD). Week 10 Value: 11. Previous Value: 15. Change: -4

Bellinger is a really perplexing player. Constant swing changes, hot streaks followed by lengthy cold streaks. I mean, this was a guy who batted .305 with 47 home runs just a few years back.

And that season is sort of all we have to cling to. He’s batting just .207 with a 29.6% strikeout rate. His quality of contact is nothing to write home about. There’s little to like.

But Bellinger does have seven home runs and six steals, which puts him at a roughly 15-15 pace. That has value in a rotisserie league, and the old Ron Shandler adage says that once you display a skill, you own that skill. So, there’s always that lingering possibility that Bellinger goes on a raging hot streak.

But with absolutely nothing to suggest it is imminent, we can finally begin to lower him in trade value.

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Dan Harris is a featured writer for FantasyPros. For more from Dan, check out his archive or follow him on Twitter @danharris80.