The 2021 baseball season has produced a spike in hot rookie prospects who have arrived in the majors. Accompanying the promotion of each up-and-comer, of course, is a flurry of bidding activity for their cards and collectibles.

We take a look at hot cards tied to four rookies. But first, let’s consider that the most anticipated debut hasn’t happened yet — and may be weeks, if not months, away. That would be Wander Franco, the hard-hitting shortstop in the Tampa Bay chain.

For a few days in May, Franco-mania was at a fever pitch. Why? Because the Rays dealt incumbent shortstop Willy Adames to Milwaukee. The trade fueled quick speculation that Franco would be called up. But, no, the Rays brought up Taylor Walls instead, preferring to give Franco more seasoning. The buzz, however, helped fuel the sale of a signed Franco rookie card for $198,000 at a well-timed event by Goldin Auctions.

A 2019 Bowman Wander Franco prospects card.

Wander Franco 

Prices in the treasure-hunting world of eBay were far more reasonable (assuming you can accept four-figure prices for cards featuring a player who has yet to appear in the majors as “reasonable”). Here’s a sampling of recent prices paid for Franco cards on eBay:

$4,450 on 42 bids for a 2019 signed Bowman Chrome Speckle Refractor. It was marked #197 of 299 and graded PSA 10.

$4,050 on 16 bids for a 2019 signed Chrome Atomic Refractor. Graded BGS 9.5, it was one of 100 made.

$3,955 on 37 bids for a signed Chrome Green Refractor. One of only 99 made, it graded out at BGS 9.5.

We’ll all be watching Franco closely as he continues to make his case at Triple-A Durham. For now, let’s turn our attention to four phenoms who have already made the jump.

K IS FOR KELENIC

The biggest buzz outside of Wander Franco was generated by Seattle’s Jarred Kelenic (pronounced KELL-nick). The lefty-swinging 21-year-old outfielder was drafted in 2018 by the Mets, who later that year traded him to Seattle for Robinson Cano and Edwin Diaz.

A signed 2018 Jarred Kelenic Bowman Draft rookie card.

Jarred Kelenic 

As a minor-leaguer, Kelenic hit .293 with 31 homers and 37 steals in 690 at-bats. This season, he was off to a .409 start after 10 games at AAA when he got the call to the big time. At the time, he was already a collector favorite — the subject of bidding wars on eBay. Consider these prices paid for Kelenic rookies:

$15,100 on 32 bids for an autographed 2018 Bowman Chrome Gold Refractor marked #19 of 50. It drew a Gem-Mint 10 grade from PSA.

$8,400 on 62 bids for a 2018 Chrome Black Refractor. This signed card, one of 75 produced, also graded at PSA 10.

Since Kelenic’s call-up, prices have calmed down a bit — for now. We saw signed Blue Refractor versions of his 2018 Chrome card sell for $2,949 on 38 bids (#20/150) and $2,900 on 43 bids (#126/150). Note, however, that Blue Refractors are less common than the Gold and Black Refractors cited above.

K IS ALSO FOR KIRILLOFF

Getting beckoned even earlier than Jarred Kelenic was Alex Kirilloff. The Minnesota Twins outfielder — who compiled a .318 average with 38 homers and 180 RBI in 1,109 at-bats in the minors — also got off to a slow start in the majors, notching just four hits in his first 23 at-bats. Then he caught fire, launching four home runs in three games. After a short stint on the injured list, Kirilloff returned to the Twins' lineup and continued showing flashes of his minor-league promise.

A 2016 Bowman Draft card of Alex Kirilloff.

Collectors are on board. Prices paid for Kirilloff cards in recent weeks are not quite at Kelenic’s level, but they’re on the rise:

$2,275 on 19 bids for a 2016 signed Bowman Chrome Gold Refractor. Marked #49/50, the card had been graded Mint 10 by PSA.

$1,876 on 20 bids for another signed Gold Refractor from Bowman’s 2016 Chrome set. Produced in the same limited run of 50 cards, this one also drew a PSA grade of Gem-Mint 10.

$1,001 on 32 bids for a 2016 autographed Chrome Blue Refractor, one of 150 issued.

TEXAS TORNADO

Since 2018, Adolis Garcia had been designated for assignment (the dreaded “DFA”) twice — once each by the Cardinals and Rangers. But he persevered and won a job with this year’s Texas team, and he has responded with eye-popping numbers: 16 homers, 42 RBI and seven steals in his first 51 games.

A 2018 Bowman Chrome Prospect card of Jose Adolis Garcia.

Jose Adolis Garcia 

Garcia hasn’t exactly come out of nowhere. At 28, he’s an older rookie, but he did have success in the high minors, slamming 22 and 32 homers in 2018 and 2019, respectively, in the Cardinals’ chain.

In the hobby, Garcia is still bubbling under. That said, his 2018 signed Bowman Chrome is gaining steam. In early May, we saw a Red Refractor version of the card (one of only five produced) sell for $1,975 on 31 bids. A Blue Refractor of the same card (from an edition of 150) sold for $890 on 30 bids.

MERCEDES RIDING HIGH

Yermin Mercedes is another late bloomer — a 28-year old who toiled in the minors for years before getting a chance to play at the highest level. Somehow, his impressive minor-league numbers — a .302 average and 83 homers in 2,128 at-bats — hadn’t merited a big-league role until now. But this year, the White Sox made him their DH and he responded by getting eight straight hits to start the season. Through 41 games, he was batting a robust .347 with 25 RBI. 

A Topps 70 Years of Baseball card featuring White Sox rookie Yermin Mercedes.

Yermin Mercedes 

Collectors are driving up the price of Mercedes’ autographed “70 Years of Baseball” insert card from Topps’ 2021 set. In April, a Red example, marked #1 of 10, sold for $1,780 on four bids. In the weeks that followed, two Gold examples (marked #1/25 and #11/25) brought prices of $920 on 61 bids and $910 on 60 bids. Still another Gold example (this one marked #5/25) fetched $865 on 83 bids.