The Nats lost. No big deal.
The Mets won. No big deal.
The Nats lost and the Mets won. Big deal?
The Nats now sit 5 games out of first place. That may not seem like a big deal but the Nats never were 5 games out last year. They had a middling record at the start of June but their pace matched the Braves. Both had fast starts, though the Braves' start was faster. Both had bad Mays, though the Braves wasn't quite as bad. The Nats basically hung around despite themselves, and when the Braves wilted away starting in June the Nats took over just by playing good, not great. (Eventually the Nats would pop the clutch and play great baseball from mid August on to make the "race" seem non-existant looking back at 2014.)
The last time the Nats were 5 games out was in fact the last day of 2013. Five games is not a ton of games if you assume that the Nats are underperforming (decent guess) and the Mets are overperforming (even better guess) but let's understand a few points.
(1) Regressing to expectations does not mean radically performing in the other direction to get to the expected level in the time alloted.
Say you thought the Nats were a 95 win team to start the year. And say the Nats started, oh I don't know, 7-8. And let's say you still believe the Nats are a 95 win team. regressing to the mean does not mean the Nats will go 88-59 so they finish exactly 95-67. Instead it means that if the Nats play at a 95 win pace for the rest of the games they will be closer to expectations than they are now.
Current Pace : 76-86
Expected Pace (full season) : 95-67
Final Record assuming play at expected pace from here on : 93-69
See! Much closer to the expectation. If we had infinite games evenutally the difference between the expected pace and the last record would be close enough to be negligible. However the baseball season isn't infinite, so these slow starts matter.
The Nats have started slowly - you should adjust your expectations down a game or two. Conversely the Mets have started quickly - you have adjust your expectations up a game or two (or three - it's a pretty fast start). So if you had the Nats at 95 and the Mets at 85, maybe today you should have it as the Nats at 93 and the Mets at 88. This isn't an exact science but regardless whatever you thought about these two teams there should be no doubt the gap has closed to some degree.
(2) We have data now. Your expectations should be reevaluated.
We're in the real season now. These data are small sample sizes, true, but they are getting bigger every day and they are the data we currently have for the year. You have to now at least take into account things that have happened this season so far. For the Nats - maybe the pen is going to be a mess for a while, maybe ZNN isn't right, maybe Ramos will never hit*. For the Mets - maybe Lucas Duda is an All-Star type hitter, maybe Wilmer Flores has put it together, maybe Colon has figured out how to be good to very good at 42.
You can't say anything is set in stone just yet but you have to look at what's happened and adjust accordingly. Maybe you do nothing. Maybe you think the Mets injuries and guys obviously overperforming (like Neise - a perfectly ok back of rotation guy getting some luck) will keep them at expectations. Maybe you think the injury returns will bring the Nats back up to their level for the rest of the year. That's fine. However you can't just dismiss what's gone on. you have to look at it.
(Me - I think the Nats bullpen flaws are worth knocking them a win. I'll hold off on giving the Mets any more props until we see how these injury replacements hold up. So Nats around 92, Mets around 86... I had them as kind of an 83-84 win to start the year)
(3) The season is not static. Injuries and break-outs and runs of bad/good luck can and will happen.
Those expectation I put out there - those are just best guesses based on what I know of the guys who are playing now. But there is a 100% chance someone on the Nats and someone on the Mets will go down to injury from here to the end of the season. Who? I got no clue. But it will happen which means that what you want to have is a cushion in case it's an important guy for a long time for you, and a secondary guy for a couple weeks for them. Breakouts will likely happen too. What if it's a middle relief guy for you and a starting SS for them? And just general luck will swing. Say you go 10-11 in one-run games and they go 15-5 (hey 2012 Orioles!). Most likely the bad and good will cancel themselves out (mostly), but you don't know that for sure so you like to have some games to play with in case you get some bad luck, rather than good.
By spotting the Mets 5 games the Nats have given the Mets a cushion. If we're wrong about expectations, (possible - this is an ongoing analysis) and the Nats and Mets are closer than we think, then the Mets now have 5 games to lose that can cover some bad breaks for them or some good breaks for the Nats.
Last year the Nats did play mediocre ball for a long time and managed to still win the division in a walk. But last year was last year. If the Nats go a couple more games back 4-5 games (or more) you can say things were never this bad for the Nats last year (as "bad" as such a hole really is this early). The Mets may not be great but a few more wins in the pocket and you have to doubt they'll finish below .500 like the Braves did. The Nats may not be bad, but can you expect them to go 33-13 again to finish the year and run away with the division? This year will almost certainly be different and the Nats can't just expect to end up on top.
A lot of this worry is just remnants from that 2-6 start. The Nats are actually playing pretty well right now, 5-2 in last seven. There have been no blowout losses, some nice wins, and the offense has scored runs. They need to keep this going. Win the series today. Win the MIA and ATL series away (at least win 3 games really). Don't revert back to the bad baseball we saw early on. You may not have things work out for you like they did last year.
* there are also good things - maybe Yunel is going to have a bounce back, maybe Bryce is taking a step forward, maybe Danny can be useful - and things yet to fall in any direction - maybe Strasburg isn't right, maybe the injury returnees will have rough seasons. Same goes for Mets, they have bad things and question marks