263 F.3d 173 (1st Cir. 2001)
HOSPITAL DEL MAESTRO, Petitioner,v.NATIONAL LABOR RELATIONS BOARD, Respondent.
No.  00-1620
United States Court of Appeals For the First Circuit
Heard August 1, 2001Decided August 20, 2001

ON PETITION FOR REVIEW OF AN ORDER OF THE NATIONAL LABOR RELATIONS BOARD
James W. McCartney, with whom Cancio, Nadal, Rivera, Daz &  Berros were on brief, for petitioner.
James M. Oleske, with whom Linda Dreeben, Assistant General  Counsel and Julie F. Marcus, Attorney, were on brief, for respondent.
Before Boudin, Chief Judge, Torruella and Selya, Circuit Judges.
Per curiam.


1
This case came before the National Labor  Relations Board (the "Board") on unfair labor practice charges filed by  Rosa Berros and the Federacion Puertorriquena de Trabajadores and on  the issuance of a consolidated complaint by the Board's Puerto Rico  regional office.  After a two-day hearing, an administrative law judge  issued a decision finding that petitioner Hospital del Maestro (the  "Hospital") had violated Section 8(a)(1) of the National Labor  Relations Act (the "Act"), 29 U.S.C. §§ 151 et seq., and recommended  that the Board enter a remedial order.


2
On February 4, 2000, the Board issued an order transferring  the case to itself.  The order, which was served on the Hospital and  its counsel, stated that exceptions to the decision of the  administrative law judge were to be received by the Board on or before  March 3, 2000.  Attached to the order were excerpts from the Board's  rules and regulations relating to the filing of exceptions.  These  rules, which include the computation of time for filing, state the  following:


3
[T]he Board will accept as timely filed any  document which is hand delivered to the Board on  or before the official closing time of the  receiving office on the due date or postmarked on  the day before (or earlier than) the due date;  documents which are postmarked on or after the  due date are untimely.  "Postmarking" shall  include timely depositing the document with a  delivery service that will provide a record  showing that the document was tendered to the  delivery service in sufficient time for delivery  by the due date, but in no event later than the  day before the due date . . . .


4
N.L.R.B. Rule § 102.111(b).  The rules further state that documents may  be filed after the time prescribed therein "only upon good cause shown  based on excusable neglect and when no undue prejudice would result." Id. § 102.111(c).


5
On February 8, 2000, the Hospital requested an extension of  time in which to file its exceptions to the judge's decision and  recommended order.  The Board granted the Hospital an extension until  March 10, 2000.  On March 9, 2000, the Hospital again requested an  extension of time, specifically requesting a due date of March 14,  2000.  The Board granted the request, notifying the Hospital by letter  that the "[d]ate for receipt of exceptions and brief in Washington, DC  is extended to March 14, 2000."


6
On March 14, 2000, the Hospital mailed to the Board, by  Federal Express overnight delivery, its exceptions to the judge's  decision and recommended order.  The Board received the documents on  March 15.  That same day, the Board sent a letter advising the Hospital  that, under the provisions of § 102.111 of the Board's rules, the  exceptions were "untimely and [could not] be forwarded to the Board for  consideration."  On March 28, 2000, the Hospital filed a motion with  the Board to accept its exceptions out of time, stating as its reason  for delay that it had "misunderstood that the effective date of filing  corresponded to the day that the Exceptions were notified by mail  [sic]."  On April 5, 2000, the Board denied the Hospital's motion,  stating that "[t]he reasons provided for the late filing [did] not rise  to the level of excusable neglect."  The Board thereafter adopted pro  forma the findings, conclusions, and recommended order of the  administrative law judge.  See 29 U.S.C. § 160(c),(e).


7
In Pioneer Investment Services Co. v. Brunswick Associates  Ltd. Partnership, 507 U.S. 380 (1993), the Supreme Court examined the  phrase "excusable neglect," noting that it is "a somewhat 'elastic  concept' and is not limited strictly to omissions caused by  circumstances beyond the control of the movant."  Id. at 392.1  The  Court concluded that the determination should take into account "all  relevant circumstances," including the "the danger of prejudice . . .  , the length of the delay and its potential impact on judicial  proceedings, the reasons for the delay, . . . and whether the movant  acted in good faith."  Id. at 395.  The Hospital argues that the Board  failed to consider all of these factors and thus erroneously denied its  late filing.  We review the Board's decision for an abuse of  discretion.  Fall River Sav. Bank v. NLRB, 649 F.2d 50, 56 (1st Cir.  1981); Melrose-Wakefield Hosp. Ass'n v. NLRB, 615 F.2d 563, 567 (1st  Cir. 1980).


8
The Hospital concedes that under the Board's rules, its  exceptions were required to be received on or before March 14, 2000, or  at least postmarked prior to that date.  Its only justification for  having misunderstood those requirements, moreover, is the apparent  paradox that a mailing postmarked before March 14 but received more than one day late would be considered timely, while a mailing  postmarked on the due date and received the next day would not.  The  Hospital does indeed highlight a possible effect of the Board's rules. However, it does not come close to explaining how this hypothetical  outcome rendered the rule itself unclear or ambiguous.  We have no  basis for finding the Hospital's neglect "excusable" when there is no  proffered reason that would justify, or even plausibly explain, its  misreading of the rules.  See Mirpuri v. ACT Manufacturing, Inc., 212  F.3d 624, 631 (1st Cir. 2000) ("A misunderstanding that occurs because  a party (or his counsel) elects to read the clear, unambiguous [rules]  . . . through rose-colored glasses cannot constitute excusable  neglect.").


9
The Hospital argues that the other factors delineated in Pioneer nevertheless tip the balance in its favor.  It is true that the  delay in this case was only one day and that there was little danger of  prejudice to the other party. We may assume, moreover, that the delay  did not negatively impact the Board's proceedings and that the Hospital  acted in good faith.  All of these taken together, however, would still  not excuse an otherwise unjustified failure to abide by the Board's  deadline.  As the Eighth Circuit has correctly observed,


10
The four Pioneer factors do not carry equal  weight; the excuse given for the late filing must  have the greatest import.  While prejudice,  length of delay, and good faith might have more  relevance in a closer case, the reason-for-delay  factor will always be critical to the inquiry. .  . . [A]t the end of the day, the focus must be  upon the nature of the neglect.


11
Lowry v. McDonnell Douglas Corp., 211 F.3d 457, 463 (8th Cir. 2000). As we have already noted, the Hospital has offered no pardonable reason  why it misconstrued the plain, unambiguous meaning of the Board's  rules.  The favorable juxtaposition of the other Pioneer factors does  not, therefore, excuse the Hospital's oversight.  We conclude that the  Board did not abuse its discretion in finding that the Hospital's  stated reason for its untimely filing did not rise to the level of  "excusable neglect."


12
Affirmed.



Notes:


1
   Although Pioneer involved the bankruptcy rules, we have acknowledged  that the Court's analysis provides guidance in other contexts.  See Pratt v. Philbrook, 109 F.3d 18, 19 (1st Cir. 1997).


