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 6 Trade Value Chart:

Risers

Tarik Skubal (SP – DET). Week 6 Value: 7. Previous Value: 2. Change: +5

Skubal has been outstanding this season, and his value was far too low for the simple reason that he was just one of those players I hadn’t thought about a lot. He wasn’t involved in many trades in leagues that had been imported into My Playbook. He pitches for one of the worst teams in baseball.

But his numbers are electric. His 2.50 ERA is backed by a 2.35 xERA, 2.09 FIP, and 2.71 xFIP. His 1.08 WHIP is a product of a strong 5% walk rate at 28.3% strikeout rate. He even has three wins already. Everything looks great.

So why move him to just a seven in the trade chart? Because it takes more than a few good starts to entirely change a preseason evaluation on a player. FantasyPros’ rest of season projections has Skubal at a 3.84 ERA and 1.26 WHIP. Steamers, Zips, and THE BAT are all in that range, too.

Maybe Skubal will allow a 0.45 HR/9 rate all year. Or a .172 xBA on his fastball. But he’ll need to do so beyond May 18th to move up significantly in trade value.

Charlie Morton (SP – ATL). Week 6 Value: 16. Previous Value: 12. Change: +4

Morton has been fairly terrible this season with a 4.93 ERA and 1.44 WHIP. His 20.6% strikeout rate is his worst since 2015, and his 11.6% walk rate his worst since his rookie year. And he’s 38 years old.

But over his last two starts, he’s allowed one run and struck out 14 in 11 innings. It hasn’t been a drastic change – just better command with his fastball which leads to his curveball being more effective.

But that’s all you should need to buy back into Morton. Because last April he pitched to a 4.76 ERA before gradually getting better in May and then pitching like a borderline ace the rest of the way. And he’s coming off a broken leg in the playoffs so it’s only natural that he might need a bit more time to find his form.

It’s not rocket science. It’s a simple fix for Morton and there is history to suggest that what we’ve seen over the last two starts might be the beginning of a turnaround.

Fallers

Tyler O’Neill (OF – STL). Week 6 Value: 14. Previous Value: 22. Change: -8

O’Neill was electric last year, batting .286 with 34 home runs and 15 steals. But it’s looked nothing like 2021 so far, as he has a .195/.256/.297 slash line through 133 plate appearances.

It’s really difficult to put up the numbers that O’Neill did last year while striking out 31.3% of the time. He was able to do so because his quality of contact was elite, as his 93 MPH average exit velocity and 52.3% hard hit rate ranked in the top seven percent of baseball.

It’s been a different story thus far, as his quality of contact metrics are below league average. So his strikeout rate, which has actually improved slightly over last year, is going to hold his numbers back.

O’Neill ranks in the 98th percentile in sprint speed so he should find his way to double-digit steals even if he can’t turn things around entirely. And we’ve seen how much upside he has, so reducing his value entirely wouldn’t be prudent. But you shouldn’t trade for him expecting elite production right now.

Austin Riley (3B – ATL). Week 6 Value: 24. Previous Value: 29. Change: -5

To be clear, you can and should still target Riley in trades. In a year in which quality of contact is down across the league, he continues to hit the ball exceedingly hard, with numbers that rank among the elite in baseball and are even better than he put up last year. He’s also walking more than ever (8.9%) and already has seven home runs.

But there are a few warning signs. His strikeout rate is 26.1% which, though not significantly, is the worst mark Riley has put up since 2019. His ground ball rate is 48.4% and his line drive rate is just 17.9%, the highest and lowest of his career, respectively.

These things could be indicative of a larger problem. Or Riley could fight his way out of them rather quickly. But without knowing for sure, he drops in value slightly.

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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.