a low five

Player: Ryan Klesko
Card: 2003 Topps Opening Day #23
Errors: Player appears to be hitting batting practice into fans. Player believes his hat is camouflage - rest of uniform does not blend in.
Comment:
Merriam-Webster's Dictionary defines "worst" as the "most unfavorable, difficult, unpleasant, or painful." I believe this is the perfect way to describe the 2003 Topps Opening Day Ryan Klesko card. I believe this is the worst card ever put on cardboard because it is from a useless a subset, it makes no sense at all and Ryan Klesko sucks.
One of the reasons the 2003 Topps Opening Day Ryan Klesko is the worst card ever produced is because it is from a useless subset. In 2003, Topps put out a regular set, a gallery set, a pristine set, a game-used memoribilia set, a heritage set, a mini set, a blue back set, a chrome set and a traded set. There was probably even more. So, the opening day set is just one more dumb picture of a player. It's like Topps is spitting in the eyes of collectors, which is bad if you want them to buy stuff.
The second reason the 2003 Topps Opening Day Ryan Klesko is the worst card ever is because it makes no sense at all. The player is shown in a military hat, but who knows why. He's hitting off a batting tee, so it looks unique but instead it's only erstwhile and stupid and no one wants a card like that. Also, it also does not seem to have anything to do with opening day.
Finally, the 2003 Topps Opening Day Ryan Klesko is the worst card ever because Ryan Klesko sucks. He's only hit over .300 two times and he grounded into 7 double plays, both very poor statistics. He also struck out 86 times which is one of the worst things you can do because it hurts your team and doesn't add any runs. He also only got one triple, which is not many even for something hard like a triple.
There are many, many bad cards ever invented in the world. But only one can be the worst card of all time in the entire universe. Because it is from a useless subset, it makes no sense at all and Ryan Klesko sucks, the 2003 Topps Opening Day Ryan Klesko is the worst card that was ever made.
Scoring: INT

a ballpark tragedy

Player: Freddie Patek
Card: 1980 O-Pee-Chee #356 (A Canadian May Day salute)
Errors: Player using oversized Dairy Queen helmet. One armed batter. Stadium appears to be leaning slightly left.
Comments:

"Now with Angels" A play, in three acts
ACT I
(A typical Quebec Province home. A fire is lit in the corner, where an old woman sits knitting a red and white scarf. A young man, JOHNNIE PATEK rushes into the house. He is holding up a package for the audience to see.)
JOHNNIE PATEK: Mother come quick, the new cards are here! The new cards are here! Finally, we will see Freddie in his American baseball uniform!
SARA PATEK: Oh my, what a day! Ever since we moved to this typical Quebec Province home, it is so hard to find U.S. baseball cards. What a joy it will be to see my beloved son in his powerful light blue American baseball uniform. Let me put down my maple syrup to get a better look.
(JOHNNIE PATEK rips open the package. Mother and son eagerly flip through the cards, tossing bits of cardboard on the floor as they go. When they reach the 356th card, both SARA PATEK and JOHNNIE PATEK gasp. Lights flash.)
SARA PATEK: What’s this? It can’t be! Now with Angels? My diminutive, but beloved, Freddie is….dead!
Scene.

ACT II
(A long, angular preacher stands in front of a packed church. An oversized portrait of Freddie Patek is propped up against a black, empty coffin. Mourners can be heard weeping in the first few rows. The audience joins the sermon in progress.)
FATHER MATTHEW KRANEPOOL: …and Freddie told me: “Father, in the big leagues, stealing isn’t a sin. It gets you a raise!”
That was the Freddie we knew. Funny. Dedicated. A family man. He may not have been the biggest player on the field, but he had guts. And that made him - at least in Bill James's estimation - the 14th best parishioner this church has ever known.
And so, it is with anguished hearts, we start Freddie on his final voyage, to be with Angels. As the pallbearers carry this symbolic coffin out, I invite the congregation to…
(Suddenly, a door swings open. The crowd turns and FATHER MATTHEW KRANEPOOL stops, mid-sentence. A man in white pants, stirrups and a navy blue baseball cap walks in.)
FREDDIE PATEK: Mom? Johnnie? They told me down at the General Canadian Store that everyone was at the church for a funeral. Who died?
SARA PATEK: But how can it be? I thought you were….with the Angels!
Scene.

ACT III
(A corporate office in London, Ontario. Several men in dark gray suits are sitting around a wide, oblong cedar table. FREDDIE PATEK sits at the end, holding a cherry red baseball bat.)
CORPORATE EXECUTIVE: Mr. Patek, the O-Pee-Chee Company sincerely regrets the zany antics caused by this unfortunate circumstance. As you can see on this legally binding document, we are prepared to offer a $20,000,000 US settlement for the pain and suffering your family endured. Normally, this sort of payment might be impossible, but we recently won the Irish Lotto so it should be no problem.
Of course, you understand that as Canadians we feel terrible about the entire incident. We hope you continue to do business with the O-Pee-Chee brand.
FREDDIE PATEK: No hard feelings, boys. Besides, it could have been worse.
CORPORATE EXECUTIVE: Excuse me? How’s that?
FREDDIE PATEK: I could have been traded...to the Yankees!
Everyone at table laughs awkwardly as lights fade.
END

Scoring: 2-4-3-4

size matters

Player: Bobby Knoop
Card: 1971 Topps #506
Errors: Playing in front of one (blurry) fan. Player wearing a light blue uniform, with matching belt. Player wearing long sleeve shirt at spring training.
Comments: Facts: Patient is Major League baseball player. Came in to office today (8/5/70) complaining of declining batting average, reduced power. Feels inadequate at the plate.
History: Player started career with California Angels, finishing 24th, then 18th in MVP voting in his second and third seasons. Those years were highlighted by a .269 average in 1965, followed by 17 homers and 11 triples in 1966. Last year, patient batted just .229 with only 5 home runs. Gold Glove fielding remains unaffected.
Diagnosis: In this physician's opinion, patient is suffering from TBS, also known as Tiny Bat Syndrome. Patient appears to be using a Little League bat, or possibly a novelty giveaway bat, during actual Major League games. Tiny bat leaves patient unable to reach any pitches thrown over outside part of the plate. On the rare occasion when player did make contact, bat shattered and splinters blinded opposing catcher Ray Fosse.
Recommendations: Drink plenty of fluids. Get plenty of rest. Take ibuprofin for any pain or fever. Do not operate heavy machinery. Borrow regulation Major League baseball bat from teammate Bill Melton (3B) or Carlos May (OF). Physician does not recommend borrowing bat from Gail Hopkins (1B). May substitute. No refills.
Scoring: F4