one of those days

常常搞不清楚這兩句。
one of those days ----a bad day not your day
one of these days-----someday; in some situation like this one.

下面這句是兩天前這次經典賽的義大利強打者所講的話，
第一句的he指的是義大利隊的打擊教練。
"He really kind of nailed home some points for me," Denorfia said. "It just ended up being one of those days where the ball just hits the barrel. They don't come around very often, and I'm just really happy it came around today."Denorfia was not the only Italian to come up big.
我強烈的懷疑，他表現那麼好，怎麼會用這句呢?他是不是用錯了，
我覺得應該是one of these days 才對。

另外今天沙巴西亞表現不好，教練就說了，one of those days, 就合乎邏輯。
"It's going to happen, and that's why it's Spring Training," Yankees manager Joe Girardi said. "He just wasn't sharp today, that's all. Am I concerned? No. It's one of those days you're going to experience during Spring Training."

三月19日補充今天記者訪問洋基投張伯倫，要補充的這一句，跟標題很像。
"It's kind of six of one and a half-dozen of the other. It's going to be a debate for a while. I'm going to have a bad start and everyone is going to say I should go back to the 'pen. It's going to be one of those things that's probably going to be talked about for a while."

It's just one of those things.
It is something that couldn't have been prevented.; It is an unfortunate thing caused by fate.
something that you say when you are talking about a bad event or situation that you cannot prevent or change