BoxRec

In April 2010 Pavlik would lose the middleweight title to Sergio Martinez and he came in at 159.5 pounds at the weigh in. In 2010 (October) Pacquiao would win the vacant Junior Middleweight title against Antonio Margarito. But let's rewrite history a bit.

Let's say immediately after Manny defeated Joshua Clottey there began talks for a superfight showdown with Kelly Pavlik in a catchweight fight for the vacant Junior Middleweight title. There is a little bit of wiggle room saying they can come in 3 lb over or 3 lb under 154. Martinez is given step aside money for this to take place.

Can Pacquiao win against Pavlik or would Pavlik simply be too big and too strong for Pacquiao?

no idea how the weight would impact pavlik, so im throwing that aside and judging based on the mw pavlik we saw

pavlik was no mug, he was basic but his jab and right hand were good heavy shots, and he was so much bigger than manny. he's not just magarito plodding forward eating shots, he could actually box at a distance. manny didnt really work his way in on opponents either, he usually just kinda lept at them and could get away with it because he was so fast, but against pavlik he'd have so much more distance to close and i think he'd struggle to do it

pavlik for me

If it's at 154 it probably wouldn't suit Pavlik who was already a fairly big Middleweight, but if it's at 157 or higher...or hell even if Pavlik could get a nutritionist who could help him take the weight off in a healthy manner. Ultimately I think he's just too big and too strong for Pac.

He's not better than Pac, but eventualy size is too much, and I think that's the case here.

Pavlik is 6'2.
Manny is 5'5.
That's 9" in height difference.
Pavlik has a modest reach for his height, at 75".
Manny has a 67" reach.
That's an 8" difference.
I think that Pavlik would win by Tko, between rounds 8-10.

Pavlik was Very heavy handed. Good stamina too. Naturally quite strong and durable.
I remember his bouts versus Bronco McKart, Zertuche, and Jermaine Taylor. Especially the first Taylor bout.
Manny was knocked cold by Marquez, so he's not iron jawed. And also, he's not that hard to hit. Decent defense, but not particularly good. And good speed and power for his size, but this wouldn't be enough. Therefore I don't see him holding up to Pavlik's continuous pressure and force.