Fantasy Baseball Trade Analyzer

How to read the number

Every player is scored on a 0 to 10,000 scale, where 10,000 is the most valuable player in the pool under your settings. The number is not a ranking. It is a measure of how much better a player is than the man you would have to start instead of him, which is why changing your league size moves it: in a 10-team league the waiver wire is stacked and the alternative is good, so nobody looks special. In a 16-team league the alternative is grim.

A gap under 5% is noise and the tool says so. Under 10%, it is close enough that your own roster should break the tie. Anything past 30% is the kind of offer you send once and do not mention again.

The formula, in full

Most calculators call their model a secret sauce. Here is ours, in the order it runs:

raw       = sum of five category z-scores   (roto)
          = season points                  (points leagues)

surplus   = raw − replacement(best eligible position)

base      = max(0, surplus) ÷ best surplus in the pool × 10,000

value     = base × ageFactor(age)

side      = Σ  value(i) × λ^(i−1)     players sorted best first

In roto, a player's raw score is the sum of his z-scores in the five standard categories, so runs, home runs, RBI, stolen bases and average for hitters, and wins, saves, strikeouts, earned run average and WHIP for pitchers. Rate categories are weighted by playing time before they are normalised, because hitting .300 across 600 at-bats moves your league average far more than hitting .300 across 60, and an unweighted z-score cannot tell those apart. Production is a recency-weighted average of the last three seasons at weights of 1, 0.5 and 0.25, normalised over the seasons a player actually appeared in, so a rookie is judged on his rookie year rather than punished for not existing in 2023.

Replacement is the last player at that position who is rostered in a league your size, not the last one who starts. That distinction matters for a trade tool: the real question is what you could get for free instead, and the answer sits behind everyone's bench. Replacement is also capped at a common baseline for all hitters, because any hitter can fill a utility slot. Without that cap, a bat-only slugger would be measured against a weaker alternative than an outfielder with the identical line, which would make the less flexible player worth more. What survives the cap is real scarcity: catcher, where the last rostered catcher genuinely is worse than the last rostered hitter, and where the premium is therefore earned rather than invented.

ageFactor compares expected production at the player's next-season age against his age when he produced the stats we measured, on a curve that peaks at 27 and 28. In redraft it looks one year ahead and barely moves anything. Switch the tool to dynasty and it averages the next six seasons at a 15% annual discount, which is where a 24-year-old and a 34-year-old stop being worth the same.

Why three good players do not equal one great one

This is the part every other calculator gets wrong, and it is the reason people screenshot them to complain. Add the players on each side together and three decent regulars will out-value a superstar every time. Managers know that is false, which is why they stop trusting the tool.

The fix is the last line of the formula. Players on a side are sorted best first and each one after the first is discounted by λ for each place down the list, so in a 12-team league the second player arrives at 78% of his standalone value, the third at 61%, the fourth at 47%. Nobody joins your roster for free. The second player in a deal has to displace whoever was in that slot, and the fourth is probably riding your bench.

λ moves with league size, because the man being displaced moves with league size. In a 10-team league there is real talent on waivers and the depth you receive is nearly free to replace, so consolidating into one star is strongly favoured and λ drops to 0.72. In a 16-team league replacement is dire and depth genuinely counts, so λ rises to 0.88. Set your league size honestly and the 3-for-1 verdicts change with it.

How position eligibility is worked out

Fantasy eligibility is not an opinion about where someone plays. It is a count of games at a position, so this tool counts them: any player with 10 or more games at a spot in the 2025 regular season is eligible there, derived from Retrosheet's game-by-game fielding records. Yahoo uses five starts or ten appearances, ESPN uses twenty games, and 10 sits between them. Designated hitter is counted the same way, which is how bat-only players end up valued against the utility slot rather than against a position they never field. If your league rewards a genuine utility player, the multi-position names in the picker are the ones to look at.

Positions are shown next to every name in the search box, along with the team. That is not decoration. Three different players who appeared in 2025 are called Luis García and two are called Luis Castillo, and the name on its own cannot tell you which is the Astros starter and which is the second baseman.

What this tool does not know

It runs on 2025 production, not 2026 projections. It has no injury data, so a pitcher who finished the season hurt still looks like his stat line. Teams shown are each player's last team of the 2025 season, which means a winter move is not reflected yet, and the label says last team rather than pretending to be live. Prospects with no big-league record are absent entirely, because there is nothing factual to value them on.

None of that makes the verdict useless. It makes it a starting point for the argument rather than the end of it, and a tool that tells you where it is blind is worth more than one that does not. If a verdict here looks wrong to you, read the reasoning underneath it. The disagreement is usually in an assumption you can now see, which is the entire point of publishing the formula.

Settled the argument? Copy the link under any verdict and paste it into your league chat. It carries the whole trade and your settings, so the other manager sees exactly what you saw instead of a screenshot. Then go and lose a different argument in 162-0, where you draft nine players and chase a perfect season.

Frequently asked questions

What is a fantasy baseball trade analyzer?

A fantasy baseball trade analyzer prices the players on each side of a proposed trade and tells you which side comes out ahead. The useful ones account for your league's scoring, size and position scarcity instead of ranking players in a vacuum. This one values every player against the last player rostered in a league your size, then explains how it got there.

Are trade analyzers worth using?

Yes, as a sanity check rather than a ruling. An analyzer reliably catches the deals that are badly one-sided, and it settles the arguments where both managers are guessing. It cannot see your standings, your injuries or the categories you have already locked up, so treat a close result as a tie and decide that one yourself.

How to use a trade analyzer effectively?

Set your league size and scoring before you read anything, because both change the answer. Then read the reasoning rather than the number. A 6% gap is noise. A trade can win on total value and still hurt you if it piles into a category you already lead, which is why the verdict here names the categories that moved.

How accurate are trade analyzers?

Accurate enough to rank players sensibly, not accurate enough to trust on close calls. Every analyzer is built on past production plus assumptions about the future. This one runs on 2025 records and knows nothing about injuries, trades or role changes since. Treat any gap under roughly 10% as a coin flip.

Which AI is best for fantasy baseball?

For trade maths, none of them. General-purpose chatbots invent statistics and cannot check their own arithmetic, which is the one thing that matters here. This analyzer applies a fixed formula to real Retrosheet records, so the same trade always returns the same answer and you can read the working. Use an AI for waiver chatter, not valuation.

Where the data comes from

Player identities, names and birth dates come from the Chadwick Bureau Register, under ODC-By 1.0. Batting, pitching and fielding records come from Retrosheet. Values are our own model, described above in full. Ages are calculated fresh on every page load rather than stored, so they never drift. The pool covers 1,093 players with 2025 playing time.

The information used here was obtained free of charge from and is copyrighted by Retrosheet. Interested parties may contact Retrosheet at www.retrosheet.org.

SportsMonkie is an independent project and is not affiliated with, endorsed by, or sponsored by Major League Baseball or any MLB team. Player names and factual statistics are reported for informational purposes. No player images or team marks are used.