Hello Babytech. I cannot say for sure why. It is sad the traffic was there & is gone. I am still learning too. I do know your success is much greater than many and less than some. Far greater than I have on seasonal articles. Kudos! Opportunity will knock on the door next year for sure.
First thoughts were the money trail. Pondering my market place for readers. 75% are in the county & most are in the city I live. Google analytics will show easily where who reads what.
I agree with you the 16th is Father's Day. Yet, ponder when your article went online? April offered a lead time of near 2-1/2 months / 10 weeks for spending.
The cycle for holiday gift giving or expenses follows Ponder spending.
Jan 1 New Year
Jan 21 Martin Luther King Day
Feb 14 Valentine Day
Feb 18 President Day
Mar 31 Easter Sunday
Apr 15 Tax Day
May 5 Cinco de Mayo
May 12 Mother's Day
May 27 Memorial Day
June 16 Father's Day
Pay cycles are sometimes weekly. Bi-monthly commonly is on the 1st and 15th more than on the 15th and 30th. Bi-weekly is odd & cycles back & forth a week with month end. That is a common today. Monthly tends to be at end of month, the 28th since a check is received the same date even with leap years.
Next, consider credit cards usage & billing cycles.
With the calendar the shift may have moved to July 4th with funds. The pay period ended on the 1st or near to. Off my head if someone is going to buy a Father's day gift after the 1st, paying rent & etc. more than likely it will be an incidental expense. I know with friends those incidental funds are split between the kids enabling them to purchase a gift for dad.
Seasonal articles are a mystery. I converted many of my poems with prose & poetry to Valentine's day articles doing well with them. I converted some back and unpublished the rest until next year.
I liked many of the items you offered. Some could be converted to July 4th bar-b-q & even a late father's day gift converting with a title change, editing & etc. Tying with mom's day into the overall editing offers one article for three purposes with common ideas. Horse racing calls that a "trifecta" = three winners and one ticket.
A base article that could easily be converted with minor editing, changing products, and over all theme may offer opportunity or may not. The article URL does not change, only the tittle.
Consider your success today Babytech, plan next year, and have fun, fun, fun . . . one smile at a time . . .