Why is Lulu suddenly so common?

Exhaust is nerfed. Which means, melee carries are on the loose now. Which also means peel supports are in great demand. Want something better than exhaust? Polymorph, baby.

She's broken. She got buffed a few times since last year and her kit has so much to stop anyone from oneshotting your carries. Plus her attack speed buff is amazing.

Shes always been fairly common, i see a lulu mid or top at least once every 5-10 games

Lululemon sells have gone through the roof...

after another nerf to lethality items and with the blade buff onhit ads such as kogmaw and Lucian Lulu as a protective support with the small buff she recently got (I think) she became good again. not really fan either but that's about it

A plethora of reasons.

In addition to the ones already mentioned here, I'd also add that pros are only human, and thus only have limited resources to invest into their mastery of champions. Thus, pro meta, which rewards deep mastery on champions, will always be fairly shallow in their picked champions.

Imagine a pro player having the choice to invest the time into learning two champions out of five. Out of these five, champion A has 70% effectiveness in four relevant traits (poke, peel, safety...any four), whereas every other of the five champions excels in one of the traits (having 100% effectiveness), but only gives 50% effectiveness in all the other three areas. The pro in question, as every one of his compatriots, will learn champion A, as it offers the most flexible option. In addition, he will learn one of the other four, either the one that most fits his and his team's playstyle or the one that most of his compatriots play (to enable picking it away from them).

Lulu is currently the champion A in this story, as the nerfs to Exhaust, Lethality items and the buffs to on-hit items and Fervor made peel and steroids in a support very favorable. And Lulu is effective in both of these areas, whereas also offering poke (with Glitterlance and Pix autos), offensively usable, TARGETED CC (Polymorph) and general versatility. Contrast Janna, who is the queen of peel and features a similar steroid, but is less versatile and more limited towards defensive/reactionary use of her abilities. Also, Janna's primary steroid is AD, while Lulu's is AS. AD is currently more readily available between Fervor and the increased AD on Blade, whereas AS is more sought-after (there is no comparable AS steroid in masteries, and Blade just lost AS).

Both. Yes she's been played in the LCS, but with all the assassins and divers running amok and Exhaust being nerfed, she can easily help her carries ignore both annoying groups of champions with her polymorph and her ult.

Main reason: They nerfed Malz, Zyra, and MF.

Literally that's why.

Correct me if I'm wrong but I think she is getting played in the lcs because of the assassins that and the fact that the meta is shifting to less mobile adc's that need protected.

Edit:And is really good right now