Cakert invented it in 2007 to help her players read signs better, then watched it languish in softball and field hockey semi-obscurity until this summer, when, in a Hail Mary, she mailed it to Chip Kelly.
And in an upset, the new Eagles coach mailed her back a personal check for $25 (it's $24.99 on the Web) and a thank-you note.
It's been a big help!! Great idea!! Chip Kelly
Much to her surprise, the Eagles have been using it ever since, on offense, usually wielded by Harvey, in his first year with the Eagles, who has his own sideline semaphoric system for the Signalfan, which Cakert says she herself cannot decipher.
"I have no clue what they're using it for," says Cakert (pronounced "Sack-ert"), a former softball player at Temple and coach at Atlantic City High School. "They have so much going on on the sidelines, you see Chip Kelly with his tongue out talking, somebody doing hand signals. They could be using it as a decoy for all I know."
Asked about it at his Thursday news conference, Kelly did not divulge much. "It's just another way to communicate what we're doing on game days," Kelly said.
And while the sideline flash cards on defense featuring Rocky Balboa, the Phillie Phanatic, Elvis, and the Fresh Prince of Bel Air have gotten all the attention, Cakert has seen the Eagles using the Signalfan and its inscrutable system of six baseball-bat-shaped, 11-inch blades that fan out in all directions.
"Oh, my God, I just saw it," Cakert said last week, reviewing game film at her home. "This is so exciting. We are so psyched that they would keep winning."
Which raises the question: Is mild-mannered Jill Cakert, mother of three, grandmother of two, girls' softball coach, booked-to-the-gills dental hygienist in a Jersey coast town, who has never even been to an Eagles game, a key to the now-famous See Coast offense?
"All I did, I sent Chip Kelly a note and said, I know you use color squares and pictures for signs, I thought maybe you might like this."
If nothing else, her beloved Signalfan has gone big time. If only the announcers would call it by its patented name!
Studying the films, you can see Harvey's got a system, though in the snow at one point he was beating the weatherproof PVC blades on his chest, which Cakert thinks maybe was simply to make a hand signal more visible.
But in other games, he could be seen with the blades in a Y shape, black and yellow up top, green hanging down. Other times, it's blue to his right, white to his left, red hanging down. Then there's one where it's yellow up, white down, red straight out at 3 o'clock. The Eagles would not make Harvey available to explain.
"I don't understand football enough," Cakert said. "You couldn't run a whole offense with it with those blades."
It is, to be sure, her biggest sale. She donated Kelly's money to Autism Speaks, where a portion of all her sales go. She has yet to send it to the Phillies, because she believes the major-league game's devotion to its tradition of sign-calling would make a manager hesitant. But she has sold it to high school and college softball, baseball, and field hockey coaches and the occasional basketball coach.
Before the Eagles, there was only one football team that purchased it, Mission High School in Texas, whose coach bought three but (like Kelly) would not say how he was using it. (Signaling is proprietary.)
"He said, 'Great, thanks.' " Cakert said. "I said, 'What do you use it for?' He said, 'It's great, thanks.' That was all they said."
So far, she says, she has sold Signalfans in 38 states, mostly to high school field hockey (to call plays on corners) and softball, but also to a handful of college teams, including baseball. She says she's sold as many to baseball teams as softball.
It started in 2007, when Cakert was coaching a travel softball team with two men, and the players were confused by the different styles of calling signals. Was the coach touching his nose or just brushing by his nose? Was that an indicator or an itch?
"It bothered me," she said. "I kept trying to think of a way to standardize. I thought of colors. I started messing around with shapes of actual paddles, something that looks like a bat. I tried to figure out how many colors, and ended up going to six.
"Nobody knew what it was for. I was using it from first base. I don't do things the way things are supposed to be. I don't coach from statistics; I coach from my gut."
Before long, she took it to Atlantic City High School, where she volunteered as coach. The team had its best season in years. The girls were engaged, opponents stumped. "My girls would laugh about it," she said. "I do it really easily for my girls. I say to them, 'If I slap your face, what color would it be?' So red's a slap. If I want you to steal a base, green means go. If I want a sneaky bunt, sneak is a coward, that's yellow. Blue for bunt."
In some cases, the only real sign was six blades up, she said. "If I had anything hanging down, it was a bogus sign," she said. The combinations are endless, much like the patterns in Kelly's offense.
Much like the Eagles' season, it's been a roller-coaster year for Cakert. On the day she received Kelly's note, her mom passed away after a long illness. Her second grandchild was born a month ago.
Most game days, she and her husband, Buck, head up to North Jersey to spend time with her daughter and grandchildren, heading to a local bar that carries the Eagles games. There, the regulars know what she's watching for - Cakert says it's almost like being back on the sidelines as a parent watching your kid - and cheer any Signalfan sighting.
At work, her patients are looking out for her. "Some of my patients come in and say: 'The Eagles are using your signal fan. Did you sell it to them?' " she says. "They're all in arms, they thought someone had copied it."
And while she has tirelessly tried to spread the gospel of the Signalfan, Cakert says total sales remain "under 500."
Luckily for the Eagles, the team passed .500 weeks ago. Which bolsters the idea, as Signalfan fans have been known to wonder, that at $25, Kelly may have underpaid.
"Chip Kelly validates it," says Cakert. "If nothing else happens in my life with the Signalfan, at least I made it to the Eagles."
Inquirer staff writer Zach Berman contributed to this article.