The Pretty Little Liars Season 2 finale feels like it happened a lifetime ago, but it was only less than a year ago that we were still debating who "A" singular — was.

And when Mona Vanderwaal (Janel Parrish) was first revealed as the ultimate baddie, not everyone was happy with this discovery — even us! After all, Mona was "A" in the books. The "twist" seemed too obvious, easy, and, yeah, boring.

However, now we're in the midst of what might be the show's strongest season yet, and Mona is no small part of that success. It turns out we were wrong. The twist wasn't a shock at the time, but the writers have proved they knew what they were doing when they stuck to their guns and made Mona "A".

Here are just three of the reasons why Mona being "A" was a great idea.

The "A" Team factor keeps it different. In the books, a new "A" replaced Mona, but there wasn't a team in the same way there is on the show. That alone is enough to keep viewers on our toes, and the fact that Mona isn't the leader means the head honcho still has the potential to shock us. The Mona reveal didn't blow our minds, but there are still plenty of opportunities for the writers to rock our worlds. Speaking of...
 
It set up the betrAyal perfectly. We were skeptical that the betrAyer would really surprise us, because we'd been burned once before, which made the Toby (Keegan Allen) reveal that much more effective. While the writers didn't intend for us to be so annoyed by Mona being "A", they at least used that reaction to their advantage; Toby (Keegan Allen) turning around at the end of Season 3, Episode 12: “The Lady Killer” remains one of the most shocking TV twists. Ever.

Crazy Mona is the BEST. More than anything, keeping Mona alive and a major player turned out to be an excellent move, in large part due to Janel Parrish's total commitment to Mona's insanity. Whether she's babbling incoherently in Radley, confidently hacking computer systems, or trading a few veiled barbs with Spencer (Troian Bellisario), Mona can reliably be called upon to steal any scene. We liked her before, but now that she's unleashed, she's one of the most consistently entertaining parts of the show. We have a hard time imagining PLL without her.

Do you agree, or do you still wish the first "A" was someone else? Sound off in the comments below.

Find more Pretty Little Liars spoilers here.

Catch the next episode of Pretty Little Liars on Tuesday, February 12, 2013 at 8 p.m. ET/PT on ABC Family.

Rebecca Martin is an editor at Wetpaint Entertainment. Follow her on Twitter @BeccaDMartin.