Intro to Trading in Fantasy Baseball: What to look for when making deals in April

I present to you the curious case of Julio Rodríguez. By now, many of you are familiar with the outfielder’s reputation as a slow starter. Over the course of his five-year career, Rodríguez has hit .220 with an 85 wRC+ in March/April. In every other month, he has a career average over .250 and a wRC+ over 105. He annually dominates the second half, where he is a lifetime .297 hitter with a 154 wRC+. Despite the slow starts, Rodríguez has been a 30-30 player with over 100 runs scored in two of the past three seasons.

A deeper dive on Rodríguez’s early season struggles shows that he not only looks like a worse hitter at the outset of the year; he actually is a worse hitter. His career 29.6% strikeout rate in March/April is far worse than that of any other month. His 35.0% hard-contact rate is lower than his career mark as well. And the issue of Rodríguez not looking like himself early in the season is amplified by some bad luck, as his 9.6% HR/FB rate and .304 BABIP during March/April are his worst of any month.

As you can see, slumps have many components. Players are human, and they tend to press for success during times of struggle, which can lead to negative changes in their skill set. This year has been much of the same for Rodríguez. He is slashing .152/.250/.152 while logging poor marks in strikeout rate (26.9%) and average exit velocity (86.8 mph). He has also dealt with bad luck in the form of a .219 BABIP.

A wise fantasy manager could do their research on Rodríguez each April and decide not to trade for him. After all, he’s striking out more often and not hitting the ball as hard. Best to leave his current manager to deal with this disappointing first-rounder. Of course, coming to that conclusion would have led to many missed opportunities in past seasons to buy low on a premier player.

Sometimes, we must trust that good players will find their way out of slumps.

The hard part is that we can’t be sure when a slump will end. Rodríguez tends to pick things up in May but doesn’t fully break out until July. Last year, I touted Christian Walker as a buy-low option at times during the first half. In the end, I was right — Walker posted a .799 OPS in the second half. But the buy-low rewards didn’t come for a while, as his OPS in each of the initial three months was below .700. Some managers traded for him at a discount and then ran out of patience, sending him to the waiver wire before he got his season on track.

Some excellent fantasy contributors in 2025, including Otto Lopez, Vinnie Pasquantino, Joe Adell, Brandon Lowe and Dansby Swanson, logged an OPS under .600 during April. Overall, the plan early in the season is to buy low on struggling players with solid career résumés. By all means, do your research and make educated guesses on who will turn around their slow start. When you read this column each week, I’ll be doing the same thing. But there are times when you need to trust your gut, as you can see in the case of Rodríguez.

Here are the factors I consider when making April trade decisions:

1.       Role changes. This may be the most obvious one, but players need opportunities to come out of a slump. Closers who have been removed from the ninth-inning role, batters who have had their playing time cut or starters who have lost their rotation spot are automatically crossed off the trade list.

2.       Batted-ball luck. This applies to hitters and pitchers. Players who are showing their usual skills while dealing with an uncharacteristic BABIP or HR/FB rate are great candidates to be part of a buy-low or sell-high offer.

3.       Pitcher velocity. This is the biggest indicator that a slow-starting pitcher is on his way to a poor season. Although he has fared well so far, Reynaldo López is an example of a pitcher whom I would not acquire due to a velocity dip. Velocity readings can be seen on many sites, including a player’s FanGraphs page.

4.       Pitch mix. When looking at a surging or failing pitcher, it makes sense to search for changes in their arsenal. A pitcher that has added a pitch, or one who can no longer effectively use one of their staple offerings, has a new expected baseline.

5.       Pitcher walk rates. Although this is less predictive than velocity, I try to avoid pitchers who have had a sudden jump in their walk rate. The increase in free passes could be a sign that the pitcher is dealing with a diminished arsenal or has less feel for some of their offerings.

6.       Batter strikeout rates. I know, I know – I mentioned strikeout rate as a misleading sign when it comes to Rodríguez. Still, a notable jump in whiffs is sometimes a sign that a batter isn’t seeing the ball well or is nursing an injury.

There are many other factors to consider, and it’s easy to get lost in mountains of data. Just be sure to look at each player with a wide lens and remember that slumps are part of a normal season.

Next week, I’ll use the criteria from this article to identify some specific buy-low options.