Every player on BallStreet has a share price driven entirely by on-field performance. A home run pushes a price up. A strikeout brings it down. Only recent performance counts — not career stats. No opinions, no guesswork. Just the game.
On Opening Day, every MLB player receives a share price based on their prior season WAR — Wins Above Replacement, the sport's most comprehensive measure of player value. A player who dominated last season opens high. A recovering player or rookie opens low, creating an opportunity for believers.
8–10 WAR
MVP TIER
8.0 – 10.0+ WAR
$160 – $200
Ohtani, Judge, Acuña
5–8 WAR
ALL-STAR TIER
5.0 – 7.9 WAR
$110 – $159
Betts, Ramirez, Freeman
3–5 WAR
SOLID STARTER
3.0 – 4.9 WAR
$70 – $109
Burnes, Henderson, Strider
1–3 WAR
ROLE PLAYER
1.0 – 2.9 WAR
$30 – $69
Clase, Wheeler, Lindor
ROOKIES & NO PRIOR WAR
$20 flat
Players with no prior MLB WAR open at a standardized $20. High upside, low cost — the classic value play if you believe in the prospect.
MID-SEASON CALL-UPS
$20 IPO
When a player is called up mid-season, they IPO at $20 regardless of prospect ranking. You'll always get a shot at the next big thing before they prove it.
02 · THE ROLLING WINDOW
Recent form drives price. Not ancient history.
BallStreet doesn't track cumulative season stats. It tracks what a player has done recently. Each player type has a rolling window — only events within that window affect the current price. A cold April won't haunt a player in August. That cold April is your buying opportunity.
HITTERS
30
at-bats rolling window
Covers roughly 8–9 games worth of plate appearances. Reacts to genuine hot and cold streaks without overreacting to a single bad night.
A 0-for-5 game moves the needle. A 0-for-20 week tanks the price — and creates a buy opportunity.
STARTING PITCHERS
3
starts (~60 batters faced)
Starters pitch every 5 days. Three starts covers about two weeks — enough to reflect real form without overreacting to one rough outing.
One bad start hurts, but doesn't define a starter. Two rough outings in a row? That's a real signal — and a discount.
RELIEVERS
10
appearances (~30 batters faced)
Relievers appear more often but face fewer batters each time. Ten appearances balances recency with enough of a sample to be meaningful.
Closers are the most volatile position. A blown save stings immediately. A save streak sends the price up fast.
03 · AT-BAT IMPACTS
Every outcome has a price.
The moment an at-bat ends, the price updates. The impact is a percentage of the current price — so a home run on a $50 stock moves it less in dollar terms than the same home run on a $150 stock, but the same percentage for both.
AT-BAT OUTCOME
WHY IT MATTERS
PRICE IMPACT
POSITIVE OUTCOMES
Home Run
The best single outcome in baseball
+5.0%
Triple
Rarest hit — speed and power combined
+3.5%
Double
Extra base hit, runner in scoring position
+2.5%
Stolen Base
Added on top of existing AB result
+2.0%
Single
Base hit, on base
+1.5%
Walk (BB)
On-base, shows plate discipline
+1.0%
Hit By Pitch
Minor on-base positive
+0.5%
NEGATIVE OUTCOMES
Flyout / Groundout
Standard out, ball in play
−1.0%
Caught Stealing
Failed aggression, out on bases
−2.0%
Strikeout
Weakest outcome, no contact
−2.0%
Double Play (GIDP)
Worst outcome — two outs on one swing
−3.5%
PER-BATTER OUTCOME
WHY IT MATTERS
PRICE IMPACT
POSITIVE OUTCOMES
Save Recorded
Closers only — game-ending bonus
+4.0%
Strikeout
Best per-batter outcome for a pitcher
+3.0%
Perfect Inning
Bonus on top of individual events
+2.0%
Groundout / Flyout
Standard out, ball in play
+0.5%
NEGATIVE OUTCOMES
Hit Batter
Minor free base
−1.0%
Single Allowed
Base runner on, minor damage
−1.5%
Walk Issued
Free base, poor command
−2.0%
Extra Base Hit Allowed
Runner in scoring position or more
−3.0%
Earned Run
Damage done — run scored against
−4.0%
Home Run Allowed
Worst single outcome for a pitcher
−5.0%
Blown Save
Closers only — failed to close
−5.0%
FIELDING OUTCOME
APPLIES TO
PRICE IMPACT
POSITIVE OUTCOMES
Put Out
Any fielder recording an out directly
+0.5%
Assist
Fielder who throws to record an out
+0.5%
Double Play (DP)
Fielders involved in turning two outs
+0.5%
NEGATIVE OUTCOMES
Fielding Error
Fielder who committed the error — batter unaffected
−3.0%
Batter is unaffected by errors. Reaching base on an error is not a hit — no price benefit to the batter. Only the fielder who committed it is penalized. Double play bonus is awarded to each fielder who touches the ball in the sequence — so a 6-4-3 DP gives both the shortstop and second baseman a +0.5% bonus on top of their assist credit.
OUTCOME
NOTES
PRICE IMPACT
POSITIVE OUTCOMES · CATCHERS ONLY
Put Out
Strikeout, tag play at plate, pop-up
+0.5%
Assist
Throw to another base for an out
+0.5%
Caught Stealing (CS)
Catcher throws out a baserunner — elite skill play
+3.0%
NEGATIVE OUTCOMES · CATCHERS ONLY
Passed Ball
Ball gets past catcher — catcher's fault, not pitcher's
−2.5%
Fielding Error
Dropped throw, fumbled tag, mishandled ball
−3.0%
Caught stealing is the catcher's premium event. At +3.0%, throwing out a baserunner is the single biggest positive a catcher can record — bigger than any routine put out or assist. Elite game-callers who shut down the running game are genuinely valuable shares. Passed ball vs. error: A passed ball (−2.5%) is slightly less punishing than a fielding error (−3.0%) since the pitcher's delivery is a contributing factor.
OUTCOME
NOTES
PRICE IMPACT
POSITIVE OUTCOMES · PITCHERS
Put Out
Pitcher covers first, fields a comebacker
+0.5%
Assist
Pitcher fields and throws to a base for an out
+0.5%
NEGATIVE OUTCOMES · PITCHERS ONLY
Wild Pitch
Errant delivery — pitcher's fault, not the catcher's
−3.0%
Fielding Error
Mishandled comebacker, failed coverage of first
−3.0%
Wild pitch vs. passed ball. The distinction matters here — a wild pitch is charged to the pitcher (−3.0%), a passed ball is charged to the catcher (−2.5%). The official scorer's ruling on game day determines which player takes the hit. Pitchers already have rich per-batter metrics (Ks, walks, earned runs, HR allowed) so fielding events are relatively rare additions to their price history — but they count.
04 · TRY IT YOURSELF
See the price engine live.
Pick a player type, fire at-bat events, and watch the price move in real time. This is exactly how it works on the exchange.
PRICE SIMULATOR
INTERACTIVE · NO ACCOUNT NEEDED
PLAYER TYPE
FIRE AN EVENT
Mike Trout
LAA · OF · Opening: $148.00
$148.00
—
ROLLING WINDOW (0 / 30)0% filled
EVENT FEED
Fire an event to start the simulation →
05 · GUARDRAILS
Prices can't go to zero. Or to the moon.
A 162-game season is a long time. BallStreet has four guardrails to keep prices fair and the game interesting all the way to the final out.
📉
Price Floor
15% of open
A $100 player can't fall below $15. Extended slumps hurt, but never make a player worthless.
📈
Price Ceiling
4× opening price
A $100 player can run to $400. Historic streaks are rewarded, but runaway inflation is capped.
🏥
Injury Hold
Season-ending IL
Hold an injured player at current price. If next year's opening price is higher, you pocket the difference.
⚠️
Roster Penalty
Daily cash deduction
If your league enforces roster requirements and you fall below a position minimum, a daily cash penalty is deducted from your balance — the amount is set by your commissioner. Cash cannot go negative.
❄️
Off-Day Freeze
Prices frozen
No games, no price movement. Prices only change when a bat meets a ball. Rest days are stable.
06 · TRADING STRATEGY
How smart traders use the model.
01
Buy the slump, sell the streak
A star in a 0-for-15 stretch will recover — the rolling window means their price has dipped below their true value. That's your entry point. Sell into the hot streak before the window catches up.
02
Watch the window, not just the price
A player's window tells you how many bad events are about to fall out of the calculation. If 8 strikeouts are about to leave a hitter's 30-AB window, their price is about to rebound — even before they start hitting again.
03
Closers are high-risk, high-reward
A save is +4%, a blown save is −5%. Closers can swing wildly on a single pitch. If your closer is locked in, their price climbs fast. If they're shaky, get out before the blown save cascade hits.
04
Corner the market on rising stars
Share float is limited. If you spot a breakout before your league does, buy as many shares as you can. When everyone else figures it out, there's nothing left to buy — and you're already holding the position.
Ready to trade?
Create a league, join one, or head straight to your leagues.