I looked at the last three years individually and found every win streak of three games or more. Here's the details:
May 7 - May 9 beat Astros 6-1 beat Astros 5-4 beat Astros 4-1 May 18 - May 21 beat Reds 5-0 beat Reds 5-3 beat Tigers 10-1 beat Tigers 6-2 June 13 - June 16 beat Mets 3-1 beat Astros 1-0 beat Astros 7-3 beat Astros 5-4 June 21 - June 25 beat Orioles 9-3 beat Orioles 5-4 beat Red Sox 3-1 beat Red Sox 5-4 July 3 - July 5 beat Nationals 10-2 beat Astros 5-3 beat Astros 5-1 | April 16 - April 18 beat Reds 4-3 beat Reds 5-4 beat Reds 5-3 April 27 - April 29 beat Brewers 7-3 beat Brewers 6-5 beat Dodgers 2-0 May 4 - May 6 beat Cubs 3-2 beat Cubs 4-2 beat Cubs 11-1 June 30 - July 2 beat Cubs 2-0 beat Phillies 3-2 beat Phillies 2-0 Sept 17 - Sept 22 beat Diamondbacks 4-3 beat Diamondbacks 9-6 beat Diamondbacks 4-3 beat Cardinals 5-2 beat Cardinals 11-6 | April 20 - April 22 beat Marlins 8-0 beat Marlins 3-2 beat Marlins 7-4 May 16 - May 20 beat Rockies 7-4 beat Rockies 11-4 beat Nationals 12-7 beat Nationals 8-5 beat Nationals 2-1 June 1 - June 4 beat Mets 8-5 beat Mets 3-1 beat Mets 11-6 June 24 - June 27 beat Indians 10-6 beat Indians 3-2 beat Indians 5-3 beat Royals 5-3 beat Royals 6-2 August 17 - August 22 beat Brewers 9-5 beat Brewers 5-2 beat Brewers 3-1 beat Reds 5-2 beat Reds 12-2 Sept 30 - October 2 beat Cubs 4-0 beat Cubs 8-2 beat Reds 3-1 |
You can see that most of those are 3-4 game streaks, the Pirates have only won five games in a row three times since 2009. They had a six game winning streak in 2008 as they swept the Giants and took the first three games of a four game set against the Braves. The last time they had a streak longer than six was way back in 2004 when they won ten games in a row, beating the Reds twice, Cardinals three times, Brewers four times, and Marlins once before losing.
The Pirates aren't a horrible baseball team anymore. They can compete with the rest of the league and have the ability to win any game they play, they just aren't to the level where they can rattle off a bunch of wins in a row. Right now it seems like they have a pitching staff that should enable them to string some together this win, but you aren't going to go on a lot of streaks regardless of how well you pitch if you only score two runs a game.
If the Pirates want to make a run at .500 this year and break this horrible streak, they're going to have to go on some winning streaks. So far this year they have only won two games in a row twice and haven't been able to win three in a row yet. All that is despite having one of the best starting rotations in the league thus far; disappointing.