PITTSBURGH -- For a rivalry to really work, a few elements have to be in order: Both teams have to be good, they have to have a lot on the line every time they play, and they have to -- at least between the lines -- not like each other very much.
The Cubs and Pirates appear to fit all of the above criteria and, with that in mind, boy, has this National League Central rivalry become a doozy.
Playing the series opener at PNC Park Monday night -- their first meeting since last year's hotly contested NL Wild Card Game -- the Cubs pulled away from the Pirates with a four-run fifth frame to win, 7-2. Later in the game, one player from each team was plunked.
Jason Hammel hit Pirates outfielder Starling Marte to lead off the sixth, and Cubs infielder Ben Zobrist was plunked by Kyle Lobstein when he led off the next frame. The result? Unhappiness on both sides, especially after each dugout then was warned by home-plate umpire Laz Diaz.
But hold on. This was, according to Cubs manager Joe Maddon, all part of the fun.
Fun?

"It's always fun to vent, isn't it?" he said. "We all vent. It's the worst possible thing you can do for your health long-term is to hold that stuff in. So I had to get that out."
Said Pirates manager Clint Hurdle: "I think it's just a reaction. It's just guys being guys."
The managers weren't the only ones riled up. Pirates catcher Francisco Cervelli -- whom Maddon mentioned pregame as someone who belongs to the same gym as his wife and is a "good dude, a real good dude" -- directed some of his ire toward the Cubs' dugout.
"I understand they protect their teammates," Cervelli said. "I've got to protect mine. You get mad, OK, get mad. You keep talking, talking … it's my guy on the mound, so I've got to protect him. I didn't know what they were saying. I just heard a lot of people talking."
"I know there was some yelling going on, but baseball's a very emotional game, so it's going to happen," said Lobstein, who was left waiting as the back-and-forth played out. "It's boys playing a game. Just move on from it."
Friction between the two teams is not new, of course. It dates back to last October at PNC Park when the two teams officially became Not Friends.

Highlights from that Wild Card Game were two-fold: Jake Arrieta's gem that dashed the Pirates' hopes to advance in the postseason, and a benches-clearing incident that resulted in the slow death of a perfectly serviceable Gatorade cooler that unwittingly got in the way of Sean Rodriguez's fists.
So, there's history here. That makes incidents like Monday, which resulted in nothing more than some chirping by both managers and perhaps a little extra adrenaline kicking in on the part of the players, slightly more intriguing. It makes you want to lean in a little, just to make sure you don't miss anything.
Postgame comments were tempered as players cooled down, and all parties involved spoke carefully about the hit batsmen.
"I can obviously only speak for myself, and I wasn't throwing at Marte intentionally. That was a pitch inside, and with him you can't miss over the plate," Hammel said. "If I'm going to go in I'm going to make sure I miss off, and obviously it ran up and in. But a lot of intensity there, probably a lot made of it because of the way things went last year in the Wild Card Game. It's a very heated rivalry."
Zobrist, a Cubs newcomer who was on his way to winning a World Series ring with the Royals when the Cubs and Pirates clashed in the Wild Card showdown, could only speak about the here and now.
"After [he was hit by the pitch] I thought, 'Oh yeah, I forgot, we hit one of their guys," Zobrist said. "Obviously, they took exception to it. We got that pitch, too. It's just a matter of judging intentions. As a team you're trying to think, 'Was that intentional or was it not?' I think in that situation it was pretty clear."
It's all part of the gamesmanship that can make an otherwise ho-hum baseball game intriguing. Maddon appeared downright amused by the questions fired at him after the game, including inquiries about challenging a slide rule play in the seventh that helped to delay the game nearly 10 minutes.

"Being a real novice with the play at second base -- I think we all are -- I had no clue what I was doing," he said. "I just knew that I could challenge. So at that particular juncture, why not? Bottom of the seventh inning, give it a shot. Why not?"
Asked if it was accurate to say the Pirates and Cubs don't like each other, Maddon opted to laud the general rivalry between the two teams. He also indicated he was going off-topic on purpose, "so I don't comment on the [hit-by-pitch]."
"It's an actual organic rivalry," Maddon said. "I really don't like contrived rivalries. I have no time for that. This is legitimate. It's gone on for many years. I think it's great. It's great for baseball, it's great for the fanbases. It's great for the players, it's interesting. It's pertinent. I really enjoy that stuff."