He landed more significant strikes than Pacquiao did against him, in his first ever pro fight. I reckon he'd be twice as good the next time he fights.
I was a little drunk last night, but assuming Mayweather is still good enough to beat most of the other fighters about, McGregor would give them a good go.
If you're going by the Compubox numbers, then you're reading them out of context.
Mayweather-Pacquiao numbers were this:
Pacquiao - 81 out of 429 (19%)
Mayweather - 148 out of 435 (34%)
Let's look at today's numbers:
McGregor - 111 out of 430 (26%)
Mayweather - 170 out of 320 (53%)
These stats are meaningless unless seen in the context of the fights. Mayweather-Pacquio had both fighters throwing at low percentages, because Floyd spent most of that fight touching and moving. Pacquiao couldn't hit him, because Floyd remained elusive.
Today, Floyd spent 3 rounds sizing Conor up, and spent the remaining 7 backing Conor and peppering him with his straight right. Conor countered a few times, but not once did he land clean. Floyd would never have tried that with Pacquiao, because Pacquiao had blindingly fast hands, and was capable of unleashing multi-punch combos.
Conor couldn't land one clean punch after round 3. In fact, he was so badly gassed that anyone with above-average power would have certainly put him down in the 5th round. Also telling that Conor, despite being the bigger guy, kept clinching Floyd repeatedly.
Then also consider the difference in size between McGregor and Pacquiao. Pacquiao is 5'5, with a 170 cm reach, and a walking weight of 145. McGregor is 5'9, with a 183 cm reach, and a walking weight of 170.
Basically, comparing McGregor's punch stats to Pacquiao's is meaningless without considering size, styles and the nature of the fight.
Conor was outclassed and outmatched. Manny was outrun and frustrated. There's a big difference between the two.